diff --git a/tests/wpt/metadata-layout-2020/2dcontext/pixel-manipulation/2d.imageData.get.large.crash.html.ini b/tests/wpt/metadata-layout-2020/2dcontext/pixel-manipulation/2d.imageData.get.large.crash.html.ini
new file mode 100644
index 00000000000..2333dfb7389
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/2dcontext/pixel-manipulation/2d.imageData.get.large.crash.html.ini
@@ -0,0 +1,2 @@
+[2d.imageData.get.large.crash.html]
+  expected: CRASH
diff --git a/tests/wpt/metadata-layout-2020/2dcontext/video/2d.video.invalid.html.ini b/tests/wpt/metadata-layout-2020/2dcontext/video/2d.video.invalid.html.ini
new file mode 100644
index 00000000000..de473e60ca3
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/2dcontext/video/2d.video.invalid.html.ini
@@ -0,0 +1,4 @@
+[2d.video.invalid.html]
+  [Verify test doesn't crash with invalid video.]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/FileAPI/url/url-in-tags-revoke.window.js.ini b/tests/wpt/metadata-layout-2020/FileAPI/url/url-in-tags-revoke.window.js.ini
index 76b44d9e9cf..3605e8f3fc9 100644
--- a/tests/wpt/metadata-layout-2020/FileAPI/url/url-in-tags-revoke.window.js.ini
+++ b/tests/wpt/metadata-layout-2020/FileAPI/url/url-in-tags-revoke.window.js.ini
@@ -4,7 +4,7 @@
     expected: TIMEOUT
 
   [Opening a blob URL in a new window immediately before revoking it works.]
-    expected: FAIL
+    expected: TIMEOUT
 
   [Fetching a blob URL immediately before revoking it works in an iframe.]
     expected: FAIL
diff --git a/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-004.html.ini b/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-004.html.ini
deleted file mode 100644
index 4bfb0c2053a..00000000000
--- a/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-004.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[hit-test-floats-004.html]
-  [Miss float below something else]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-layout-2020/css/CSS2/linebox/inline-negative-margin-001.html.ini b/tests/wpt/metadata-layout-2020/css/CSS2/linebox/inline-negative-margin-001.html.ini
index cb2edcb5dcd..6425f4beda1 100644
--- a/tests/wpt/metadata-layout-2020/css/CSS2/linebox/inline-negative-margin-001.html.ini
+++ b/tests/wpt/metadata-layout-2020/css/CSS2/linebox/inline-negative-margin-001.html.ini
@@ -5,6 +5,9 @@
   [[data-expected-height\] 7]
     expected: FAIL
 
-  [[data-expected-height\] 4]
+  [[data-expected-height\] 1]
+    expected: FAIL
+
+  [[data-expected-height\] 2]
     expected: FAIL
 
diff --git a/tests/wpt/metadata-layout-2020/css/css-animations/Document-getAnimations.tentative.html.ini b/tests/wpt/metadata-layout-2020/css/css-animations/Document-getAnimations.tentative.html.ini
index e4237b19a4c..69b2f23d33f 100644
--- a/tests/wpt/metadata-layout-2020/css/css-animations/Document-getAnimations.tentative.html.ini
+++ b/tests/wpt/metadata-layout-2020/css/css-animations/Document-getAnimations.tentative.html.ini
@@ -50,3 +50,6 @@
   [Yet-to-start CSS Animations are returned]
     expected: FAIL
 
+  [pseudo element with replaced target does not affect animation ordering]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/css/css-backgrounds/background-attachment-margin-root-001.html.ini b/tests/wpt/metadata-layout-2020/css/css-backgrounds/background-attachment-margin-root-001.html.ini
new file mode 100644
index 00000000000..94df7e19f4d
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/css/css-backgrounds/background-attachment-margin-root-001.html.ini
@@ -0,0 +1,2 @@
+[background-attachment-margin-root-001.html]
+  expected: FAIL
diff --git a/tests/wpt/metadata-layout-2020/css/css-backgrounds/background-attachment-margin-root-002.html.ini b/tests/wpt/metadata-layout-2020/css/css-backgrounds/background-attachment-margin-root-002.html.ini
new file mode 100644
index 00000000000..864e9504eaa
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/css/css-backgrounds/background-attachment-margin-root-002.html.ini
@@ -0,0 +1,2 @@
+[background-attachment-margin-root-002.html]
+  expected: FAIL
diff --git a/tests/wpt/metadata-layout-2020/css/css-images/image-orientation/svg-image-orientation-none.html.ini b/tests/wpt/metadata-layout-2020/css/css-images/image-orientation/svg-image-orientation-none.html.ini
new file mode 100644
index 00000000000..6f19466fb16
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/css/css-images/image-orientation/svg-image-orientation-none.html.ini
@@ -0,0 +1,2 @@
+[svg-image-orientation-none.html]
+  expected: FAIL
diff --git a/tests/wpt/metadata-layout-2020/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini b/tests/wpt/metadata-layout-2020/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini
index 70a00a101f6..e35a452a186 100644
--- a/tests/wpt/metadata-layout-2020/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini
+++ b/tests/wpt/metadata-layout-2020/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini
@@ -1,2 +1,2 @@
 [no-transition-from-ua-to-blocking-stylesheet.html]
-  expected: FAIL
+  expected: TIMEOUT
diff --git a/tests/wpt/metadata-layout-2020/css/cssom-view/elementFromPosition.html.ini b/tests/wpt/metadata-layout-2020/css/cssom-view/elementFromPosition.html.ini
index c131078eace..23c61ede1a1 100644
--- a/tests/wpt/metadata-layout-2020/css/cssom-view/elementFromPosition.html.ini
+++ b/tests/wpt/metadata-layout-2020/css/cssom-view/elementFromPosition.html.ini
@@ -17,3 +17,6 @@
   [test the top of layer]
     expected: FAIL
 
+  [test some point of the element: top left corner]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/css/cssom-view/elementsFromPoint-iframes.html.ini b/tests/wpt/metadata-layout-2020/css/cssom-view/elementsFromPoint-iframes.html.ini
index 6ef8bb1049f..171592fc08f 100644
--- a/tests/wpt/metadata-layout-2020/css/cssom-view/elementsFromPoint-iframes.html.ini
+++ b/tests/wpt/metadata-layout-2020/css/cssom-view/elementsFromPoint-iframes.html.ini
@@ -2,6 +2,3 @@
   [elementsFromPoint on the root document for points in iframe elements]
     expected: FAIL
 
-  [elementsFromPoint on inner documents]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-layout-2020/fetch/content-type/response.window.js.ini b/tests/wpt/metadata-layout-2020/fetch/content-type/response.window.js.ini
index 495998a990a..d75f3b61459 100644
--- a/tests/wpt/metadata-layout-2020/fetch/content-type/response.window.js.ini
+++ b/tests/wpt/metadata-layout-2020/fetch/content-type/response.window.js.ini
@@ -318,12 +318,18 @@
   [<iframe>: combined response Content-Type: text/html;" \\" text/plain]
     expected: FAIL
 
-  [<iframe>: combined response Content-Type: text/html */*;charset=gbk]
-    expected: FAIL
-
   [<iframe>: separate response Content-Type: text/html;" \\" text/plain]
     expected: FAIL
 
-  [<iframe>: separate response Content-Type: text/plain */*;charset=gbk]
+  [<iframe>: combined response Content-Type: */* text/html]
+    expected: FAIL
+
+  [<iframe>: separate response Content-Type: text/html */*]
+    expected: FAIL
+
+  [<iframe>: separate response Content-Type: text/html;x=" text/plain]
+    expected: FAIL
+
+  [<iframe>: combined response Content-Type: text/html;x=" text/plain]
     expected: FAIL
 
diff --git a/tests/wpt/metadata-layout-2020/fetch/content-type/script.window.js.ini b/tests/wpt/metadata-layout-2020/fetch/content-type/script.window.js.ini
index c7413d589dc..5c001592859 100644
--- a/tests/wpt/metadata-layout-2020/fetch/content-type/script.window.js.ini
+++ b/tests/wpt/metadata-layout-2020/fetch/content-type/script.window.js.ini
@@ -59,6 +59,3 @@
   [separate text/javascript;charset=windows-1252 error text/javascript]
     expected: FAIL
 
-  [separate text/javascript;charset=windows-1252  text/javascript]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-layout-2020/fetch/nosniff/parsing-nosniff.window.js.ini b/tests/wpt/metadata-layout-2020/fetch/nosniff/parsing-nosniff.window.js.ini
index 87c807a49ff..ef3edb78985 100644
--- a/tests/wpt/metadata-layout-2020/fetch/nosniff/parsing-nosniff.window.js.ini
+++ b/tests/wpt/metadata-layout-2020/fetch/nosniff/parsing-nosniff.window.js.ini
@@ -11,3 +11,6 @@
   [X-Content-Type-Options%3A%20nosniff%0C]
     expected: FAIL
 
+  [X-Content-Type-Options%3A%20%22nosniFF%22]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_1.html.ini b/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_1.html.ini
deleted file mode 100644
index 87b07c3e670..00000000000
--- a/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_1.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[traverse_the_history_1.html]
-  [Multiple history traversals from the same task]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_2.html.ini b/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_2.html.ini
deleted file mode 100644
index 75d75b4cda2..00000000000
--- a/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_2.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[traverse_the_history_2.html]
-  [Multiple history traversals, last would be aborted]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_3.html.ini b/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_3.html.ini
deleted file mode 100644
index 51f8272a6de..00000000000
--- a/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_3.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[traverse_the_history_3.html]
-  [Multiple history traversals, last would be aborted]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_2.html.ini b/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_4.html.ini
similarity index 71%
rename from tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_2.html.ini
rename to tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_4.html.ini
index 75d75b4cda2..385376c7321 100644
--- a/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_2.html.ini
+++ b/tests/wpt/metadata-layout-2020/html/browsers/history/the-history-interface/traverse_the_history_4.html.ini
@@ -1,4 +1,4 @@
-[traverse_the_history_2.html]
+[traverse_the_history_4.html]
   [Multiple history traversals, last would be aborted]
     expected: FAIL
 
diff --git a/tests/wpt/metadata-layout-2020/html/browsers/origin/cross-origin-objects/cross-origin-objects-on-new-window.html.ini b/tests/wpt/metadata-layout-2020/html/browsers/origin/cross-origin-objects/cross-origin-objects-on-new-window.html.ini
new file mode 100644
index 00000000000..735a9a75a2a
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/html/browsers/origin/cross-origin-objects/cross-origin-objects-on-new-window.html.ini
@@ -0,0 +1,2 @@
+[cross-origin-objects-on-new-window.html]
+  expected: TIMEOUT
diff --git a/tests/wpt/metadata-layout-2020/html/interaction/focus/the-autofocus-attribute/supported-elements.html.ini b/tests/wpt/metadata-layout-2020/html/interaction/focus/the-autofocus-attribute/supported-elements.html.ini
index 3538891dae8..af14e19a466 100644
--- a/tests/wpt/metadata-layout-2020/html/interaction/focus/the-autofocus-attribute/supported-elements.html.ini
+++ b/tests/wpt/metadata-layout-2020/html/interaction/focus/the-autofocus-attribute/supported-elements.html.ini
@@ -4,14 +4,17 @@
     expected: FAIL
 
   [Host element with delegatesFocus including no focusable descendants should be skipped]
-    expected: FAIL
+    expected: NOTRUN
 
   [Element with tabindex should support autofocus]
-    expected: FAIL
-
-  [Area element should support autofocus]
     expected: TIMEOUT
 
-  [Host element with delegatesFocus should support autofocus]
-    expected: FAIL
+  [Area element should support autofocus]
+    expected: NOTRUN
+
+  [Host element with delegatesFocus should support autofocus]
+    expected: NOTRUN
+
+  [Non-HTMLElement should not support autofocus]
+    expected: NOTRUN
 
diff --git a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-2.html.ini b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-2.html.ini
index 0407f0cc2b7..9eb581fcf1f 100644
--- a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-2.html.ini
+++ b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-2.html.ini
@@ -1,5 +1,5 @@
 [iframe_sandbox_popups_nonescaping-2.html]
-  expected: TIMEOUT
+  expected: CRASH
   [Check that popups from a sandboxed iframe do not escape the sandbox]
     expected: NOTRUN
 
diff --git a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-3.html.ini b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-3.html.ini
index f4f994c5d6f..0fbc49ea1c1 100644
--- a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-3.html.ini
+++ b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-3.html.ini
@@ -1,5 +1,5 @@
 [iframe_sandbox_popups_nonescaping-3.html]
-  expected: TIMEOUT
+  expected: CRASH
   [Check that popups from a sandboxed iframe do not escape the sandbox]
     expected: NOTRUN
 
diff --git a/tests/wpt/metadata-layout-2020/html/semantics/scripting-1/the-script-element/script-onerror-insertion-point-2.html.ini b/tests/wpt/metadata-layout-2020/html/semantics/scripting-1/the-script-element/script-onerror-insertion-point-2.html.ini
deleted file mode 100644
index 178680e5d14..00000000000
--- a/tests/wpt/metadata-layout-2020/html/semantics/scripting-1/the-script-element/script-onerror-insertion-point-2.html.ini
+++ /dev/null
@@ -1,2 +0,0 @@
-[script-onerror-insertion-point-2.html]
-  expected: TIMEOUT
diff --git a/tests/wpt/metadata-layout-2020/html/webappapis/scripting/events/compile-event-handler-settings-objects.html.ini b/tests/wpt/metadata-layout-2020/html/webappapis/scripting/events/compile-event-handler-settings-objects.html.ini
index 5602ea31dbe..dbec6f2c2ff 100644
--- a/tests/wpt/metadata-layout-2020/html/webappapis/scripting/events/compile-event-handler-settings-objects.html.ini
+++ b/tests/wpt/metadata-layout-2020/html/webappapis/scripting/events/compile-event-handler-settings-objects.html.ini
@@ -3,6 +3,3 @@
   [The incumbent settings object while executing the compiled callback via Web IDL's invoke must be that of the node document]
     expected: TIMEOUT
 
-  [The entry settings object while executing the compiled callback via Web IDL's invoke must be that of the node document]
-    expected: TIMEOUT
-
diff --git a/tests/wpt/metadata-layout-2020/url/url-setters-stripping.any.js.ini b/tests/wpt/metadata-layout-2020/url/url-setters-stripping.any.js.ini
new file mode 100644
index 00000000000..ae1ba2692bb
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/url/url-setters-stripping.any.js.ini
@@ -0,0 +1,327 @@
+[url-setters-stripping.any.html]
+  [Setting pathname with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting protocol with U+0000 before inserted colon (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting search with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting host with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting hash with middle U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting protocol with U+001F before inserted colon (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting port with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with U+0000 before inserted colon (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with U+001F before inserted colon (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting hash with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting search with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with middle U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting host with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+001F (wpt++:)]
+    expected: FAIL
+
+
+[url-setters-stripping.any.worker.html]
+  [Setting pathname with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting protocol with U+0000 before inserted colon (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting search with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting host with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting hash with middle U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting protocol with U+001F before inserted colon (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting port with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with U+0000 before inserted colon (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with U+001F before inserted colon (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting hash with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting search with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with middle U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting host with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+001F (wpt++:)]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels.html.ini b/tests/wpt/metadata-layout-2020/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels.html.ini
index 4b6bd9284e0..846e1dac805 100644
--- a/tests/wpt/metadata-layout-2020/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels.html.ini
+++ b/tests/wpt/metadata-layout-2020/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels.html.ini
@@ -110,3 +110,6 @@
   [X Rendered audio for channel 5 does not equal [0,0.0626220703125,0.125030517578125,0.18695068359375,0.24810791015625,0.308319091796875,0.3673095703125,0.42486572265625,0.480743408203125,0.53472900390625,0.58660888671875,0.636199951171875,0.68328857421875,0.727691650390625,0.76922607421875,0.8077392578125...\] with an element-wise tolerance of {"absoluteThreshold":0.000030517578125,"relativeThreshold":0}.\n\tIndex\tActual\t\t\tExpected\t\tAbsError\t\tRelError\t\tTest threshold\n\t[1\]\t3.6732959747314453e-1\t6.2622070312500000e-2\t3.0470752716064453e-1\t4.8658168859649127e+0\t3.0517578125000000e-5\n\t[2\]\t6.8329977989196777e-1\t1.2503051757812500e-1\t5.5826926231384277e-1\t4.4650639949963384e+0\t3.0517578125000000e-5\n\t[3\]\t9.0373212099075317e-1\t1.8695068359375000e-1\t7.1678143739700317e-1\t3.8340669508039502e+0\t3.0517578125000000e-5\n\t[4\]\t9.9780619144439697e-1\t2.4810791015625000e-1\t7.4969828128814697e-1\t3.0216621502152523e+0\t3.0517578125000000e-5\n\t[5\]\t9.5236867666244507e-1\t3.0831909179687500e-1\t6.4404958486557007e-1\t2.0889059484187866e+0\t3.0517578125000000e-5\n\t...and 40524 more errors.\n\tMax AbsError of 1.9999794363975525e+0 at index of 37272.\n\t[37272\]\t9.9997943639755249e-1\t-1.0000000000000000e+0\t1.9999794363975525e+0\t1.9999794363975525e+0\t3.0517578125000000e-5\n\tMax RelError of Infinity at index of 12348.\n\t[12348\]\t9.5105654001235962e-1\t0.0000000000000000e+0\t9.5105654001235962e-1\tInfinity\t3.0517578125000000e-5\n]
     expected: FAIL
 
+  [X Rendered audio for channel 5 does not equal [0,0.0626220703125,0.125030517578125,0.18695068359375,0.24810791015625,0.308319091796875,0.3673095703125,0.42486572265625,0.480743408203125,0.53472900390625,0.58660888671875,0.636199951171875,0.68328857421875,0.727691650390625,0.76922607421875,0.8077392578125...\] with an element-wise tolerance of {"absoluteThreshold":0.000030517578125,"relativeThreshold":0}.\n\tIndex\tActual\t\t\tExpected\t\tAbsError\t\tRelError\t\tTest threshold\n\t[1\]\t3.6732959747314453e-1\t6.2622070312500000e-2\t3.0470752716064453e-1\t4.8658168859649127e+0\t3.0517578125000000e-5\n\t[2\]\t6.8329977989196777e-1\t1.2503051757812500e-1\t5.5826926231384277e-1\t4.4650639949963384e+0\t3.0517578125000000e-5\n\t[3\]\t9.0373212099075317e-1\t1.8695068359375000e-1\t7.1678143739700317e-1\t3.8340669508039502e+0\t3.0517578125000000e-5\n\t[4\]\t9.9780619144439697e-1\t2.4810791015625000e-1\t7.4969828128814697e-1\t3.0216621502152523e+0\t3.0517578125000000e-5\n\t[5\]\t9.5236867666244507e-1\t3.0831909179687500e-1\t6.4404958486557007e-1\t2.0889059484187866e+0\t3.0517578125000000e-5\n\t...and 40521 more errors.\n\tMax AbsError of 1.9962286949157715e+0 at index of 40997.\n\t[40997\]\t9.9879217147827148e-1\t-9.9743652343750000e-1\t1.9962286949157715e+0\t2.0013591321441684e+0\t3.0517578125000000e-5\n\tMax RelError of Infinity at index of 12348.\n\t[12348\]\t9.5105654001235962e-1\t0.0000000000000000e+0\t9.5105654001235962e-1\tInfinity\t3.0517578125000000e-5\n]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/webmessaging/without-ports/017.html.ini b/tests/wpt/metadata-layout-2020/webmessaging/without-ports/017.html.ini
deleted file mode 100644
index 064cf47545b..00000000000
--- a/tests/wpt/metadata-layout-2020/webmessaging/without-ports/017.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[017.html]
-  expected: TIMEOUT
-  [origin of the script that invoked the method, about:blank]
-    expected: TIMEOUT
-
diff --git a/tests/wpt/metadata-layout-2020/workers/postMessage_block.https.html.ini b/tests/wpt/metadata-layout-2020/workers/postMessage_block.https.html.ini
new file mode 100644
index 00000000000..3ada9b78833
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/workers/postMessage_block.https.html.ini
@@ -0,0 +1,4 @@
+[postMessage_block.https.html]
+  [postMessage and block]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/2dcontext/pixel-manipulation/2d.imageData.get.large.crash.html.ini b/tests/wpt/metadata/2dcontext/pixel-manipulation/2d.imageData.get.large.crash.html.ini
new file mode 100644
index 00000000000..2333dfb7389
--- /dev/null
+++ b/tests/wpt/metadata/2dcontext/pixel-manipulation/2d.imageData.get.large.crash.html.ini
@@ -0,0 +1,2 @@
+[2d.imageData.get.large.crash.html]
+  expected: CRASH
diff --git a/tests/wpt/metadata/2dcontext/video/2d.video.invalid.html.ini b/tests/wpt/metadata/2dcontext/video/2d.video.invalid.html.ini
new file mode 100644
index 00000000000..de473e60ca3
--- /dev/null
+++ b/tests/wpt/metadata/2dcontext/video/2d.video.invalid.html.ini
@@ -0,0 +1,4 @@
+[2d.video.invalid.html]
+  [Verify test doesn't crash with invalid video.]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/FileAPI/url/url-in-tags-revoke.window.js.ini b/tests/wpt/metadata/FileAPI/url/url-in-tags-revoke.window.js.ini
index d4f62ed7113..faa00f45ecf 100644
--- a/tests/wpt/metadata/FileAPI/url/url-in-tags-revoke.window.js.ini
+++ b/tests/wpt/metadata/FileAPI/url/url-in-tags-revoke.window.js.ini
@@ -7,7 +7,7 @@
     expected: FAIL
 
   [Opening a blob URL in a new window immediately before revoking it works.]
-    expected: FAIL
+    expected: TIMEOUT
 
   [Opening a blob URL in a noopener about:blank window immediately before revoking it works.]
     expected: TIMEOUT
diff --git a/tests/wpt/metadata/MANIFEST.json b/tests/wpt/metadata/MANIFEST.json
index 955212296ce..8dad8a64a28 100644
--- a/tests/wpt/metadata/MANIFEST.json
+++ b/tests/wpt/metadata/MANIFEST.json
@@ -110,6 +110,13 @@
        {}
       ]
      ],
+     "negative-item-margins-crash.html": [
+      "d5f9365b5ec1be0e62435651a70d1baeb6d8083a",
+      [
+       null,
+       {}
+      ]
+     ],
      "padding-overflow-crash.html": [
       "fd0c333fabadb073b9977a63de6a8c5c3ed79042",
       [
@@ -10332,13 +10339,6 @@
      ]
     },
     "css-speech": {
-     "Integer.html": [
-      "40d7bf55b4b2174ad69b0de0240d6e38beef55ef",
-      [
-       null,
-       {}
-      ]
-     ],
      "age-declarations-001.html": [
       "a1437d8a227b082720d66e0d8d0c965e9f4131e3",
       [
@@ -10380,6 +10380,13 @@
        null,
        {}
       ]
+     ],
+     "voice-family-integer.html": [
+      "40d7bf55b4b2174ad69b0de0240d6e38beef55ef",
+      [
+       null,
+       {}
+      ]
      ]
     },
     "css-text": {
@@ -117835,6 +117842,32 @@
        ]
       ]
      },
+     "background-attachment-margin-root-001.html": [
+      "88bc2845e8b6a6e24ca33547e704deab28e046bb",
+      [
+       null,
+       [
+        [
+         "/css/css-backgrounds/background-attachment-margin-root-001-ref.html",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
+     "background-attachment-margin-root-002.html": [
+      "4ee882f9da95ea884851a373d283092031a7cb2e",
+      [
+       null,
+       [
+        [
+         "/css/css-backgrounds/background-attachment-margin-root-002-ref.html",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
      "background-clip": {
       "clip-rounded-corner.html": [
        "3453c5bc8f5e45667ba20a1e6276a08e4b1be714",
@@ -144954,6 +144987,606 @@
        ]
       ]
      },
+     "masonry.tentative": {
+      "masonry-align-content-001.html": [
+       "dfefd998c65c8a071faeef0991f8b9bfe9132a60",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-align-content-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-align-content-002.html": [
+       "75b82654fea45cf8460abbdd0c0b7df8ed8b2afe",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-align-content-002-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-align-content-003.html": [
+       "ae58e79cb2b4752e08f01e3548705cdf3af1e554",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-align-content-003-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-align-content-004.html": [
+       "3f07aa1fe75b5f0a0e62e559f1d878052ebd31b3",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-align-content-004-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-align-tracks-001.html": [
+       "4ff3e61087597bee960e30d245bf3aae255cec72",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-align-tracks-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-align-tracks-multi-001.html": [
+       "2dcdfe4b4bef33806f29a1a70b64037ee167f2c7",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-align-tracks-multi-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-align-tracks-stretch-001.html": [
+       "d2fede7a8edcd0ddec450baa2961d767ba89a81a",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-align-tracks-stretch-002.html": [
+       "1631ac3c07d3f97c30ebcad6f16f9b3cd29cd4d4",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-002-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-fragmentation-001.html": [
+       "69182c5425e80f91f883d8c670ff2fe4394ccadc",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-fragmentation-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-fragmentation-002.html": [
+       "01c4de00b56af8a3c4c082244934ff0aafd5a410",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-fragmentation-002-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-fragmentation-003.html": [
+       "fe150e7f8382f9f0cb151400cdc3e9aa0b0846f3",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-fragmentation-003-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-fragmentation-004.html": [
+       "ddfc1bb331f788833e5a4e7c003fc0d4b130a984",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-fragmentation-004-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-fragmentation-005.html": [
+       "8315b8f2b557cc56459acffc682099cc5d10a447",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-fragmentation-005-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-fragmentation-006.html": [
+       "9dab0ddc9b6b3c73a7c5727b56a8890a4c9a41e5",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-fragmentation-006-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-gap-001.html": [
+       "17873d1e96c3f996bc6dcaaa08eb41325acbaa7a",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-gap-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-grid-item-content-baseline-001.html": [
+       "60d11653b3f231a07ad7aa493a0effeae7720671",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-grid-item-content-baseline-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-grid-item-self-baseline-001.html": [
+       "bb486d983d966476f24d142675c77f7907300705",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-grid-item-self-baseline-002a.html": [
+       "f89217c68e04fc2e20b680bec4705f8c8a961fba",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002a-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-grid-item-self-baseline-002b.html": [
+       "eae435707d2298c7ca9d5baa507c020f5288c9ab",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002b-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-grid-placement-named-lines-001.html": [
+       "b6745f6973b4c0dfd180b778df5d73ef3ca853e3",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-grid-placement-named-lines-002.html": [
+       "0ad0dfcea370dd12f0ebf61c5675552f93b6ce6b",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-002-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-intrinsic-sizing-001.html": [
+       "0f6cdb14954214e81931aa2a5cf80873dc589d84",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-001-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-intrinsic-sizing-002.html": [
+       "db83299bf5061f0c7209089facdfef277f129a5c",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-002-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-intrinsic-sizing-003.html": [
+       "e43bc86c9b9571f362e37572be57f0b019ccbfb8",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-003-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-intrinsic-sizing-004.html": [
+       "5365208c00f8220ae6427920eae846c0986cbec7",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-004-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-intrinsic-sizing-005.html": [
+       "cf9b680869f58373a24a87e105dd518c9bb2ef13",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-005-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-intrinsic-sizing-006.html": [
+       "49fd53bb79b1e97c011c61db7aeb863067db0a01",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-006-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "masonry-item-placement-001.html": [
+       "2f8cfbfacc21aade2e06f858f83abb0af468d7bf",
+       [
+        null,
+        [
+         [
+          "/css/css-grid/masonry.tentative/masonry-item-placement-001-ref.html",
+          "=="
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        }
@@ -516921,7 +517890,7 @@
         "script_metadata": [
          [
           "global",
-          "!default,worker"
+          "worker"
          ]
         ]
        }
@@ -516935,14 +517904,14 @@
       ]
      ],
      "onconnect.any.js": [
-      "85546f2d11df3907f592ee52b7a8ef4faec1f338",
+      "d43a9921833d2ccc4da438fcee19e0d6f8745bf5",
       [
        "workers/examples/onconnect.any.sharedworker.html",
        {
         "script_metadata": [
          [
           "global",
-          "!default,sharedworker"
+          "sharedworker"
          ]
         ]
        }
@@ -516950,14 +517919,14 @@
      ]
     },
     "importscripts_mime.any.js": [
-     "d7e215853f4d924a75df076e36dba3ead6fd6ee2",
+     "950edb28d16a855516d8155c2b5c03db793d3567",
      [
       "workers/importscripts_mime.any.serviceworker.html",
       {
        "script_metadata": [
         [
          "global",
-         "!window,worker"
+         "worker"
         ]
        ]
       }
@@ -516968,7 +517937,7 @@
        "script_metadata": [
         [
          "global",
-         "!window,worker"
+         "worker"
         ]
        ]
       }
@@ -516979,7 +517948,7 @@
        "script_metadata": [
         [
          "global",
-         "!window,worker"
+         "worker"
         ]
        ]
       }
@@ -517167,14 +518136,14 @@
         ]
        ],
        "returns-same-object.any.js": [
-        "ba9be9ce8a8534bfc17aa20f1df119ce4efad934",
+        "dd3560f040cd92145b387ecb14cd4f0563604859",
         [
          "workers/interfaces/WorkerGlobalScope/location/returns-same-object.any.serviceworker.html",
          {
           "script_metadata": [
            [
             "global",
-            "!default,worker"
+            "worker"
            ]
           ]
          }
@@ -517185,7 +518154,7 @@
           "script_metadata": [
            [
             "global",
-            "!default,worker"
+            "worker"
            ]
           ]
          }
@@ -517196,7 +518165,7 @@
           "script_metadata": [
            [
             "global",
-            "!default,worker"
+            "worker"
            ]
           ]
          }
@@ -517248,14 +518217,14 @@
        ]
       },
       "self.any.js": [
-       "a1aacc08808bcb15473977b933d29944b02def2f",
+       "64b4ee2faefb6e13e475a1ebf82fa49f41bf6c72",
        [
         "workers/interfaces/WorkerGlobalScope/self.any.serviceworker.html",
         {
          "script_metadata": [
           [
            "global",
-           "!default,worker"
+           "worker"
           ]
          ]
         }
@@ -517266,7 +518235,7 @@
          "script_metadata": [
           [
            "global",
-           "!default,worker"
+           "worker"
           ]
          ]
         }
@@ -517277,7 +518246,7 @@
          "script_metadata": [
           [
            "global",
-           "!default,worker"
+           "worker"
           ]
          ]
         }
@@ -517758,6 +518727,13 @@
       {}
      ]
     ],
+    "postMessage_block.https.html": [
+     "c3e69f6193f09c20b66aea779e7e2c31889bff65",
+     [
+      null,
+      {}
+     ]
+    ],
     "postMessage_clone_port.htm": [
      "b1d7b84e3c09d06b2b39f9722e656787a174f5a8",
      [
@@ -517847,28 +518823,28 @@
        ]
       ],
       "003.any.js": [
-       "ea95deda29889254e0e1c83bebb58cdc04363c2d",
+       "b404f77321d0019d0196ffa2524c5ef910eca388",
        [
         "workers/semantics/interface-objects/003.any.sharedworker.html",
         {
          "script_metadata": [
           [
            "global",
-           "!default,sharedworker"
+           "sharedworker"
           ]
          ]
         }
        ]
       ],
       "004.any.js": [
-       "358af74ca2c2bda6a0805ec8bded53a92674eb17",
+       "65f59a0b377886cc96053f7d7b8a3c8199a8594b",
        [
         "workers/semantics/interface-objects/004.any.sharedworker.html",
         {
          "script_metadata": [
           [
            "global",
-           "!default,sharedworker"
+           "sharedworker"
           ]
          ]
         }
diff --git a/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-004.html.ini b/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-004.html.ini
deleted file mode 100644
index 4bfb0c2053a..00000000000
--- a/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-004.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[hit-test-floats-004.html]
-  [Miss float below something else]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/CSS2/linebox/inline-negative-margin-001.html.ini b/tests/wpt/metadata/css/CSS2/linebox/inline-negative-margin-001.html.ini
index 94a3570d26b..076c791cd3d 100644
--- a/tests/wpt/metadata/css/CSS2/linebox/inline-negative-margin-001.html.ini
+++ b/tests/wpt/metadata/css/CSS2/linebox/inline-negative-margin-001.html.ini
@@ -8,6 +8,9 @@
   [[data-expected-height\] 3]
     expected: FAIL
 
-  [[data-expected-height\] 4]
+  [[data-expected-height\] 1]
+    expected: FAIL
+
+  [[data-expected-height\] 2]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/css/css-animations/Document-getAnimations.tentative.html.ini b/tests/wpt/metadata/css/css-animations/Document-getAnimations.tentative.html.ini
index 68c854940f8..70bdeaa4b0c 100644
--- a/tests/wpt/metadata/css/css-animations/Document-getAnimations.tentative.html.ini
+++ b/tests/wpt/metadata/css/css-animations/Document-getAnimations.tentative.html.ini
@@ -50,3 +50,6 @@
   [Order of CSS Animations - free animation vs CSS Transitions]
     expected: FAIL
 
+  [pseudo element with replaced target does not affect animation ordering]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/css-backgrounds/background-attachment-margin-root-001.html.ini b/tests/wpt/metadata/css/css-backgrounds/background-attachment-margin-root-001.html.ini
new file mode 100644
index 00000000000..94df7e19f4d
--- /dev/null
+++ b/tests/wpt/metadata/css/css-backgrounds/background-attachment-margin-root-001.html.ini
@@ -0,0 +1,2 @@
+[background-attachment-margin-root-001.html]
+  expected: FAIL
diff --git a/tests/wpt/metadata/css/css-backgrounds/background-attachment-margin-root-002.html.ini b/tests/wpt/metadata/css/css-backgrounds/background-attachment-margin-root-002.html.ini
new file mode 100644
index 00000000000..864e9504eaa
--- /dev/null
+++ b/tests/wpt/metadata/css/css-backgrounds/background-attachment-margin-root-002.html.ini
@@ -0,0 +1,2 @@
+[background-attachment-margin-root-002.html]
+  expected: FAIL
diff --git a/tests/wpt/metadata/css/css-images/image-orientation/svg-image-orientation-none.html.ini b/tests/wpt/metadata/css/css-images/image-orientation/svg-image-orientation-none.html.ini
new file mode 100644
index 00000000000..6f19466fb16
--- /dev/null
+++ b/tests/wpt/metadata/css/css-images/image-orientation/svg-image-orientation-none.html.ini
@@ -0,0 +1,2 @@
+[svg-image-orientation-none.html]
+  expected: FAIL
diff --git a/tests/wpt/metadata/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini b/tests/wpt/metadata/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini
index 70a00a101f6..e35a452a186 100644
--- a/tests/wpt/metadata/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini
@@ -1,2 +1,2 @@
 [no-transition-from-ua-to-blocking-stylesheet.html]
-  expected: FAIL
+  expected: TIMEOUT
diff --git a/tests/wpt/metadata/css/cssom-view/elementFromPosition.html.ini b/tests/wpt/metadata/css/cssom-view/elementFromPosition.html.ini
index 85e94926cb3..5733d536fd3 100644
--- a/tests/wpt/metadata/css/cssom-view/elementFromPosition.html.ini
+++ b/tests/wpt/metadata/css/cssom-view/elementFromPosition.html.ini
@@ -21,3 +21,6 @@
   [test the top of layer]
     expected: FAIL
 
+  [test some point of the element: top left corner]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/cssom-view/elementsFromPoint-iframes.html.ini b/tests/wpt/metadata/css/cssom-view/elementsFromPoint-iframes.html.ini
index 6ef8bb1049f..171592fc08f 100644
--- a/tests/wpt/metadata/css/cssom-view/elementsFromPoint-iframes.html.ini
+++ b/tests/wpt/metadata/css/cssom-view/elementsFromPoint-iframes.html.ini
@@ -2,6 +2,3 @@
   [elementsFromPoint on the root document for points in iframe elements]
     expected: FAIL
 
-  [elementsFromPoint on inner documents]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/fetch/content-type/response.window.js.ini b/tests/wpt/metadata/fetch/content-type/response.window.js.ini
index bf7382f7570..f0360aaefcd 100644
--- a/tests/wpt/metadata/fetch/content-type/response.window.js.ini
+++ b/tests/wpt/metadata/fetch/content-type/response.window.js.ini
@@ -318,12 +318,18 @@
   [<iframe>: combined response Content-Type: text/html;" \\" text/plain]
     expected: FAIL
 
-  [<iframe>: combined response Content-Type: text/html */*;charset=gbk]
-    expected: FAIL
-
   [<iframe>: separate response Content-Type: text/html;" \\" text/plain]
     expected: FAIL
 
-  [<iframe>: separate response Content-Type: text/plain */*;charset=gbk]
+  [<iframe>: combined response Content-Type: */* text/html]
+    expected: FAIL
+
+  [<iframe>: separate response Content-Type: text/html */*]
+    expected: FAIL
+
+  [<iframe>: separate response Content-Type: text/html;x=" text/plain]
+    expected: FAIL
+
+  [<iframe>: combined response Content-Type: text/html;x=" text/plain]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/fetch/content-type/script.window.js.ini b/tests/wpt/metadata/fetch/content-type/script.window.js.ini
index c7413d589dc..5c001592859 100644
--- a/tests/wpt/metadata/fetch/content-type/script.window.js.ini
+++ b/tests/wpt/metadata/fetch/content-type/script.window.js.ini
@@ -59,6 +59,3 @@
   [separate text/javascript;charset=windows-1252 error text/javascript]
     expected: FAIL
 
-  [separate text/javascript;charset=windows-1252  text/javascript]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/fetch/nosniff/parsing-nosniff.window.js.ini b/tests/wpt/metadata/fetch/nosniff/parsing-nosniff.window.js.ini
index 30e1b851fd4..58de838d890 100644
--- a/tests/wpt/metadata/fetch/nosniff/parsing-nosniff.window.js.ini
+++ b/tests/wpt/metadata/fetch/nosniff/parsing-nosniff.window.js.ini
@@ -11,3 +11,6 @@
   [X-Content-Type-Options%3A%20nosniff%2C%2C%40%23%24%23%25%25%26%5E%26%5E*()()11!]
     expected: FAIL
 
+  [X-Content-Type-Options%3A%20%22nosniFF%22]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_1.html.ini b/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_1.html.ini
deleted file mode 100644
index 87b07c3e670..00000000000
--- a/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_1.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[traverse_the_history_1.html]
-  [Multiple history traversals from the same task]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_3.html.ini b/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_4.html.ini
similarity index 71%
rename from tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_3.html.ini
rename to tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_4.html.ini
index 51f8272a6de..385376c7321 100644
--- a/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_3.html.ini
+++ b/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_4.html.ini
@@ -1,4 +1,4 @@
-[traverse_the_history_3.html]
+[traverse_the_history_4.html]
   [Multiple history traversals, last would be aborted]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/html/browsers/origin/cross-origin-objects/cross-origin-objects-on-new-window.html.ini b/tests/wpt/metadata/html/browsers/origin/cross-origin-objects/cross-origin-objects-on-new-window.html.ini
new file mode 100644
index 00000000000..735a9a75a2a
--- /dev/null
+++ b/tests/wpt/metadata/html/browsers/origin/cross-origin-objects/cross-origin-objects-on-new-window.html.ini
@@ -0,0 +1,2 @@
+[cross-origin-objects-on-new-window.html]
+  expected: TIMEOUT
diff --git a/tests/wpt/metadata/html/interaction/focus/the-autofocus-attribute/supported-elements.html.ini b/tests/wpt/metadata/html/interaction/focus/the-autofocus-attribute/supported-elements.html.ini
index d1ca01ebc5f..8b743f36e1d 100644
--- a/tests/wpt/metadata/html/interaction/focus/the-autofocus-attribute/supported-elements.html.ini
+++ b/tests/wpt/metadata/html/interaction/focus/the-autofocus-attribute/supported-elements.html.ini
@@ -4,14 +4,17 @@
     expected: FAIL
 
   [Element with tabindex should support autofocus]
-    expected: FAIL
-
-  [Host element with delegatesFocus including no focusable descendants should be skipped]
-    expected: FAIL
-
-  [Area element should support autofocus]
     expected: TIMEOUT
 
-  [Host element with delegatesFocus should support autofocus]
-    expected: FAIL
+  [Host element with delegatesFocus including no focusable descendants should be skipped]
+    expected: NOTRUN
+
+  [Area element should support autofocus]
+    expected: NOTRUN
+
+  [Host element with delegatesFocus should support autofocus]
+    expected: NOTRUN
+
+  [Non-HTMLElement should not support autofocus]
+    expected: NOTRUN
 
diff --git a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-2.html.ini b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-2.html.ini
index d43f38b40cd..45d8be1c898 100644
--- a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-2.html.ini
+++ b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-2.html.ini
@@ -1,6 +1,6 @@
 [iframe_sandbox_popups_nonescaping-2.html]
   type: testharness
-  expected: TIMEOUT
+  expected: CRASH
   [Check that popups from a sandboxed iframe do not escape the sandbox]
     expected: NOTRUN
 
diff --git a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-3.html.ini b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-3.html.ini
index e440b1e38c6..71edac2c5ed 100644
--- a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-3.html.ini
+++ b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-3.html.ini
@@ -1,6 +1,6 @@
 [iframe_sandbox_popups_nonescaping-3.html]
   type: testharness
-  expected: TIMEOUT
+  expected: CRASH
   [Check that popups from a sandboxed iframe do not escape the sandbox]
     expected: NOTRUN
 
diff --git a/tests/wpt/metadata/html/semantics/scripting-1/the-script-element/script-onerror-insertion-point-2.html.ini b/tests/wpt/metadata/html/semantics/scripting-1/the-script-element/script-onerror-insertion-point-2.html.ini
deleted file mode 100644
index 178680e5d14..00000000000
--- a/tests/wpt/metadata/html/semantics/scripting-1/the-script-element/script-onerror-insertion-point-2.html.ini
+++ /dev/null
@@ -1,2 +0,0 @@
-[script-onerror-insertion-point-2.html]
-  expected: TIMEOUT
diff --git a/tests/wpt/metadata/html/webappapis/scripting/events/compile-event-handler-settings-objects.html.ini b/tests/wpt/metadata/html/webappapis/scripting/events/compile-event-handler-settings-objects.html.ini
index edae5e5adcd..0cef5158fae 100644
--- a/tests/wpt/metadata/html/webappapis/scripting/events/compile-event-handler-settings-objects.html.ini
+++ b/tests/wpt/metadata/html/webappapis/scripting/events/compile-event-handler-settings-objects.html.ini
@@ -4,6 +4,3 @@
   [The incumbent settings object while executing the compiled callback via Web IDL's invoke must be that of the node document]
     expected: TIMEOUT
 
-  [The entry settings object while executing the compiled callback via Web IDL's invoke must be that of the node document]
-    expected: TIMEOUT
-
diff --git a/tests/wpt/metadata/url/url-setters-stripping.any.js.ini b/tests/wpt/metadata/url/url-setters-stripping.any.js.ini
new file mode 100644
index 00000000000..ae1ba2692bb
--- /dev/null
+++ b/tests/wpt/metadata/url/url-setters-stripping.any.js.ini
@@ -0,0 +1,327 @@
+[url-setters-stripping.any.html]
+  [Setting pathname with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting protocol with U+0000 before inserted colon (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting search with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting host with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting hash with middle U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting protocol with U+001F before inserted colon (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting port with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with U+0000 before inserted colon (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with U+001F before inserted colon (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting hash with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting search with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with middle U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting host with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+001F (wpt++:)]
+    expected: FAIL
+
+
+[url-setters-stripping.any.worker.html]
+  [Setting pathname with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting protocol with U+0000 before inserted colon (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting search with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting host with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting search with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting hash with middle U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting protocol with U+001F before inserted colon (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with trailing U+001F (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting pathname with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting port with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with U+0000 before inserted colon (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with U+001F before inserted colon (https:)]
+    expected: FAIL
+
+  [Setting pathname with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hash with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting protocol with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+0000 (https:)]
+    expected: FAIL
+
+  [Setting hash with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting search with trailing U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting search with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with trailing U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+001F (https:)]
+    expected: FAIL
+
+  [Setting hash with middle U+0000 (https:)]
+    expected: FAIL
+
+  [Setting host with leading U+0000 (wpt++:)]
+    expected: FAIL
+
+  [Setting host with trailing U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting hostname with leading U+001F (wpt++:)]
+    expected: FAIL
+
+  [Setting port with leading U+001F (wpt++:)]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels.html.ini b/tests/wpt/metadata/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels.html.ini
index 4b430f5b101..f5c29850791 100644
--- a/tests/wpt/metadata/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels.html.ini
+++ b/tests/wpt/metadata/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels.html.ini
@@ -179,3 +179,6 @@
   [X Rendered audio for channel 5 does not equal [0,0.0626220703125,0.125030517578125,0.18695068359375,0.24810791015625,0.308319091796875,0.3673095703125,0.42486572265625,0.480743408203125,0.53472900390625,0.58660888671875,0.636199951171875,0.68328857421875,0.727691650390625,0.76922607421875,0.8077392578125...\] with an element-wise tolerance of {"absoluteThreshold":0.000030517578125,"relativeThreshold":0}.\n\tIndex\tActual\t\t\tExpected\t\tAbsError\t\tRelError\t\tTest threshold\n\t[1\]\t3.6732959747314453e-1\t6.2622070312500000e-2\t3.0470752716064453e-1\t4.8658168859649127e+0\t3.0517578125000000e-5\n\t[2\]\t6.8329977989196777e-1\t1.2503051757812500e-1\t5.5826926231384277e-1\t4.4650639949963384e+0\t3.0517578125000000e-5\n\t[3\]\t9.0373212099075317e-1\t1.8695068359375000e-1\t7.1678143739700317e-1\t3.8340669508039502e+0\t3.0517578125000000e-5\n\t[4\]\t9.9780619144439697e-1\t2.4810791015625000e-1\t7.4969828128814697e-1\t3.0216621502152523e+0\t3.0517578125000000e-5\n\t[5\]\t9.5236867666244507e-1\t3.0831909179687500e-1\t6.4404958486557007e-1\t2.0889059484187866e+0\t3.0517578125000000e-5\n\t...and 40524 more errors.\n\tMax AbsError of 1.9999794363975525e+0 at index of 37272.\n\t[37272\]\t9.9997943639755249e-1\t-1.0000000000000000e+0\t1.9999794363975525e+0\t1.9999794363975525e+0\t3.0517578125000000e-5\n\tMax RelError of Infinity at index of 12348.\n\t[12348\]\t9.5105654001235962e-1\t0.0000000000000000e+0\t9.5105654001235962e-1\tInfinity\t3.0517578125000000e-5\n]
     expected: FAIL
 
+  [X Rendered audio for channel 5 does not equal [0,0.0626220703125,0.125030517578125,0.18695068359375,0.24810791015625,0.308319091796875,0.3673095703125,0.42486572265625,0.480743408203125,0.53472900390625,0.58660888671875,0.636199951171875,0.68328857421875,0.727691650390625,0.76922607421875,0.8077392578125...\] with an element-wise tolerance of {"absoluteThreshold":0.000030517578125,"relativeThreshold":0}.\n\tIndex\tActual\t\t\tExpected\t\tAbsError\t\tRelError\t\tTest threshold\n\t[1\]\t3.6732959747314453e-1\t6.2622070312500000e-2\t3.0470752716064453e-1\t4.8658168859649127e+0\t3.0517578125000000e-5\n\t[2\]\t6.8329977989196777e-1\t1.2503051757812500e-1\t5.5826926231384277e-1\t4.4650639949963384e+0\t3.0517578125000000e-5\n\t[3\]\t9.0373212099075317e-1\t1.8695068359375000e-1\t7.1678143739700317e-1\t3.8340669508039502e+0\t3.0517578125000000e-5\n\t[4\]\t9.9780619144439697e-1\t2.4810791015625000e-1\t7.4969828128814697e-1\t3.0216621502152523e+0\t3.0517578125000000e-5\n\t[5\]\t9.5236867666244507e-1\t3.0831909179687500e-1\t6.4404958486557007e-1\t2.0889059484187866e+0\t3.0517578125000000e-5\n\t...and 40521 more errors.\n\tMax AbsError of 1.9962286949157715e+0 at index of 40997.\n\t[40997\]\t9.9879217147827148e-1\t-9.9743652343750000e-1\t1.9962286949157715e+0\t2.0013591321441684e+0\t3.0517578125000000e-5\n\tMax RelError of Infinity at index of 12348.\n\t[12348\]\t9.5105654001235962e-1\t0.0000000000000000e+0\t9.5105654001235962e-1\tInfinity\t3.0517578125000000e-5\n]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/webmessaging/without-ports/017.html.ini b/tests/wpt/metadata/webmessaging/without-ports/017.html.ini
deleted file mode 100644
index 064cf47545b..00000000000
--- a/tests/wpt/metadata/webmessaging/without-ports/017.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[017.html]
-  expected: TIMEOUT
-  [origin of the script that invoked the method, about:blank]
-    expected: TIMEOUT
-
diff --git a/tests/wpt/metadata/workers/postMessage_block.https.html.ini b/tests/wpt/metadata/workers/postMessage_block.https.html.ini
new file mode 100644
index 00000000000..3ada9b78833
--- /dev/null
+++ b/tests/wpt/metadata/workers/postMessage_block.https.html.ini
@@ -0,0 +1,4 @@
+[postMessage_block.https.html]
+  [postMessage and block]
+    expected: FAIL
+
diff --git a/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.basic.png b/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.basic.png
index 1e313371d82..70d7b046cb2 100644
Binary files a/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.basic.png and b/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.basic.png differ
diff --git a/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.maxWidth.large.png b/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.maxWidth.large.png
index 1e313371d82..70d7b046cb2 100644
Binary files a/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.maxWidth.large.png and b/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.maxWidth.large.png differ
diff --git a/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.rtl.png b/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.rtl.png
index 1e313371d82..70d7b046cb2 100644
Binary files a/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.rtl.png and b/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.fill.rtl.png differ
diff --git a/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.stroke.basic.png b/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.stroke.basic.png
index b04566f5c66..fb3b5b830d3 100644
Binary files a/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.stroke.basic.png and b/tests/wpt/web-platform-tests/2dcontext/drawing-text-to-the-canvas/2d.text.draw.stroke.basic.png differ
diff --git a/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.invalid.strokestyle.html b/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.invalid.strokestyle.html
new file mode 100644
index 00000000000..71cf7e79220
--- /dev/null
+++ b/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.invalid.strokestyle.html
@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<!-- DO NOT EDIT! This test has been generated by /2dcontext/tools/gentest.py. -->
+<title>Canvas test: 2d.line.invalid.strokestyle</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/2dcontext/resources/canvas-tests.js"></script>
+<link rel="stylesheet" href="/2dcontext/resources/canvas-tests.css">
+<body class="show_output">
+
+<h1>2d.line.invalid.strokestyle</h1>
+<p class="desc">Verify correct behavior of canvas on an invalid strokeStyle()</p>
+
+
+<p class="output">Actual output:</p>
+<canvas id="c" class="output" width="100" height="50"><p class="fallback">FAIL (fallback content)</p></canvas>
+
+<ul id="d"></ul>
+<script>
+var t = async_test("Verify correct behavior of canvas on an invalid strokeStyle()");
+_addTest(function(canvas, ctx) {
+
+ctx.strokeStyle = 'rgb(0, 255, 0)';
+ctx.strokeStyle = 'nonsense';
+ctx.lineWidth = 200;
+ctx.moveTo(0,100);
+ctx.lineTo(200,100);
+ctx.stroke();
+var imageData = ctx.getImageData(0, 0, 200, 200);
+var imgdata = imageData.data;
+_assert(imgdata[4] == 0, "imgdata[\""+(4)+"\"] == 0");
+_assert(imgdata[5] == 255, "imgdata[\""+(5)+"\"] == 255");
+_assert(imgdata[6] == 0, "imgdata[\""+(6)+"\"] == 0");
+
+
+});
+</script>
+
diff --git a/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.miter.invalid.html b/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.miter.invalid.html
index 3e6ea410004..0dcd7b59348 100644
--- a/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.miter.invalid.html
+++ b/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.miter.invalid.html
@@ -42,6 +42,18 @@ ctx.miterLimit = 1.5;
 ctx.miterLimit = NaN;
 _assertSame(ctx.miterLimit, 1.5, "ctx.miterLimit", "1.5");
 
+ctx.miterLimit = 1.5;
+ctx.miterLimit = 'string';
+_assertSame(ctx.miterLimit, 1.5, "ctx.miterLimit", "1.5");
+
+ctx.miterLimit = 1.5;
+ctx.miterLimit = true;
+_assertSame(ctx.miterLimit, 1, "ctx.miterLimit", "1");
+
+ctx.miterLimit = 1.5;
+ctx.miterLimit = false;
+_assertSame(ctx.miterLimit, 1.5, "ctx.miterLimit", "1.5");
+
 
 });
 </script>
diff --git a/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.width.invalid.html b/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.width.invalid.html
index b079fd83d9e..5db1108798d 100644
--- a/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.width.invalid.html
+++ b/tests/wpt/web-platform-tests/2dcontext/line-styles/2d.line.width.invalid.html
@@ -42,6 +42,18 @@ ctx.lineWidth = 1.5;
 ctx.lineWidth = NaN;
 _assertSame(ctx.lineWidth, 1.5, "ctx.lineWidth", "1.5");
 
+ctx.lineWidth = 1.5;
+ctx.lineWidth = 'string';
+_assertSame(ctx.lineWidth, 1.5, "ctx.lineWidth", "1.5");
+
+ctx.lineWidth = 1.5;
+ctx.lineWidth = true;
+_assertSame(ctx.lineWidth, 1, "ctx.lineWidth", "1");
+
+ctx.lineWidth = 1.5;
+ctx.lineWidth = false;
+_assertSame(ctx.lineWidth, 1.5, "ctx.lineWidth", "1.5");
+
 
 });
 </script>
diff --git a/tests/wpt/web-platform-tests/2dcontext/pixel-manipulation/2d.imageData.get.large.crash.html b/tests/wpt/web-platform-tests/2dcontext/pixel-manipulation/2d.imageData.get.large.crash.html
new file mode 100644
index 00000000000..a4d8ca0f98c
--- /dev/null
+++ b/tests/wpt/web-platform-tests/2dcontext/pixel-manipulation/2d.imageData.get.large.crash.html
@@ -0,0 +1,27 @@
+<!DOCTYPE html>
+<!-- DO NOT EDIT! This test has been generated by /2dcontext/tools/gentest.py. -->
+<title>Canvas test: 2d.imageData.get.large.crash</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/2dcontext/resources/canvas-tests.js"></script>
+<link rel="stylesheet" href="/2dcontext/resources/canvas-tests.css">
+<body class="show_output">
+
+<h1>2d.imageData.get.large.crash</h1>
+<p class="desc">Test that canvas crash when image data cannot be allocated.</p>
+
+
+<p class="output">Actual output:</p>
+<canvas id="c" class="output" width="100" height="50"><p class="fallback">FAIL (fallback content)</p></canvas>
+
+<ul id="d"></ul>
+<script>
+var t = async_test("Test that canvas crash when image data cannot be allocated.");
+_addTest(function(canvas, ctx) {
+
+assert_throws_js(TypeError, function() { ctx.getImageData(10, 0xffffffff, 2147483647, 10); });
+
+
+});
+</script>
+
diff --git a/tests/wpt/web-platform-tests/2dcontext/pixel-manipulation/2d.imageData.get.rounding.html b/tests/wpt/web-platform-tests/2dcontext/pixel-manipulation/2d.imageData.get.rounding.html
new file mode 100644
index 00000000000..025df355480
--- /dev/null
+++ b/tests/wpt/web-platform-tests/2dcontext/pixel-manipulation/2d.imageData.get.rounding.html
@@ -0,0 +1,45 @@
+<!DOCTYPE html>
+<!-- DO NOT EDIT! This test has been generated by /2dcontext/tools/gentest.py. -->
+<title>Canvas test: 2d.imageData.get.rounding</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/2dcontext/resources/canvas-tests.js"></script>
+<link rel="stylesheet" href="/2dcontext/resources/canvas-tests.css">
+<body class="show_output">
+
+<h1>2d.imageData.get.rounding</h1>
+<p class="desc">Test the handling of non-integer source coordinates in getImageData().</p>
+
+
+<p class="output">Actual output:</p>
+<canvas id="c" class="output" width="100" height="50"><p class="fallback">FAIL (fallback content)</p></canvas>
+
+<ul id="d"></ul>
+<script>
+var t = async_test("Test the handling of non-integer source coordinates in getImageData().");
+_addTest(function(canvas, ctx) {
+
+function testDimensions(sx, sy, sw, sh, width, height)
+{
+    imageData = ctx.getImageData(sx, sy, sw, sh);
+    _assert(imageData.width == width, "imageData.width == width");
+    _assert(imageData.height == height, "imageData.height == height");
+}
+
+testDimensions(0, 0, 20, 10, 20, 10);
+
+testDimensions(.1, .2, 20, 10, 20, 10);
+testDimensions(.9, .8, 20, 10, 20, 10);
+
+testDimensions(0, 0, 20.9, 10.9, 20, 10);
+testDimensions(0, 0, 20.1, 10.1, 20, 10);
+
+testDimensions(-1, -1, 20, 10, 20, 10);
+
+testDimensions(-1.1, 0, 20, 10, 20, 10);
+testDimensions(-1.9,  0, 20, 10, 20, 10);
+
+
+});
+</script>
+
diff --git a/tests/wpt/web-platform-tests/2dcontext/shadows/2d.shadow.attributes.shadowBlur.invalid.html b/tests/wpt/web-platform-tests/2dcontext/shadows/2d.shadow.attributes.shadowBlur.invalid.html
index e8d5f7bddeb..c89c107a6c5 100644
--- a/tests/wpt/web-platform-tests/2dcontext/shadows/2d.shadow.attributes.shadowBlur.invalid.html
+++ b/tests/wpt/web-platform-tests/2dcontext/shadows/2d.shadow.attributes.shadowBlur.invalid.html
@@ -35,6 +35,18 @@ ctx.shadowBlur = 1;
 ctx.shadowBlur = NaN;
 _assertSame(ctx.shadowBlur, 1, "ctx.shadowBlur", "1");
 
+ctx.shadowBlur = 1;
+ctx.shadowBlur = 'string';
+_assertSame(ctx.shadowBlur, 1, "ctx.shadowBlur", "1");
+
+ctx.shadowBlur = 1;
+ctx.shadowBlur = true;
+_assertSame(ctx.shadowBlur, 1, "ctx.shadowBlur", "1");
+
+ctx.shadowBlur = 1;
+ctx.shadowBlur = false;
+_assertSame(ctx.shadowBlur, 0, "ctx.shadowBlur", "0");
+
 
 });
 </script>
diff --git a/tests/wpt/web-platform-tests/2dcontext/shadows/2d.shadow.attributes.shadowOffset.invalid.html b/tests/wpt/web-platform-tests/2dcontext/shadows/2d.shadow.attributes.shadowOffset.invalid.html
index 913a0110da7..1b36ed80457 100644
--- a/tests/wpt/web-platform-tests/2dcontext/shadows/2d.shadow.attributes.shadowOffset.invalid.html
+++ b/tests/wpt/web-platform-tests/2dcontext/shadows/2d.shadow.attributes.shadowOffset.invalid.html
@@ -40,6 +40,27 @@ ctx.shadowOffsetY = NaN;
 _assertSame(ctx.shadowOffsetX, 1, "ctx.shadowOffsetX", "1");
 _assertSame(ctx.shadowOffsetY, 2, "ctx.shadowOffsetY", "2");
 
+ctx.shadowOffsetX = 1;
+ctx.shadowOffsetY = 2;
+ctx.shadowOffsetX = 'string';
+ctx.shadowOffsetY = 'string';
+_assertSame(ctx.shadowOffsetX, 1, "ctx.shadowOffsetX", "1");
+_assertSame(ctx.shadowOffsetY, 2, "ctx.shadowOffsetY", "2");
+
+ctx.shadowOffsetX = 1;
+ctx.shadowOffsetY = 2;
+ctx.shadowOffsetX = true;
+ctx.shadowOffsetY = true;
+_assertSame(ctx.shadowOffsetX, 1, "ctx.shadowOffsetX", "1");
+_assertSame(ctx.shadowOffsetY, 1, "ctx.shadowOffsetY", "1");
+
+ctx.shadowOffsetX = 1;
+ctx.shadowOffsetY = 2;
+ctx.shadowOffsetX = false;
+ctx.shadowOffsetY = false;
+_assertSame(ctx.shadowOffsetX, 0, "ctx.shadowOffsetX", "0");
+_assertSame(ctx.shadowOffsetY, 0, "ctx.shadowOffsetY", "0");
+
 
 });
 </script>
diff --git a/tests/wpt/web-platform-tests/2dcontext/tools/name2dir.yaml b/tests/wpt/web-platform-tests/2dcontext/tools/name2dir.yaml
index 40a04057881..90826affd91 100644
--- a/tests/wpt/web-platform-tests/2dcontext/tools/name2dir.yaml
+++ b/tests/wpt/web-platform-tests/2dcontext/tools/name2dir.yaml
@@ -32,6 +32,7 @@
 2d.text.draw.space.collapse.start:    "text-styles"
 2d.state:                             "the-canvas-state"
 2d.scrollPathIntoView:                "scroll"
+2d.video:                             "video"
 2d.canvas:                            "../html/semantics/embedded-content/the-canvas-element"
 2d.getcontext:                        "../html/semantics/embedded-content/the-canvas-element"
 2d.scaled:                            "../html/semantics/embedded-content/the-canvas-element"
diff --git a/tests/wpt/web-platform-tests/2dcontext/tools/tests2d.yaml b/tests/wpt/web-platform-tests/2dcontext/tools/tests2d.yaml
index f4d4ae5b01e..dbd8e7e3cb6 100644
--- a/tests/wpt/web-platform-tests/2dcontext/tools/tests2d.yaml
+++ b/tests/wpt/web-platform-tests/2dcontext/tools/tests2d.yaml
@@ -3762,6 +3762,18 @@
     ctx.lineWidth = NaN;
     @assert ctx.lineWidth === 1.5;
 
+    ctx.lineWidth = 1.5;
+    ctx.lineWidth = 'string';
+    @assert ctx.lineWidth === 1.5;
+
+    ctx.lineWidth = 1.5;
+    ctx.lineWidth = true;
+    @assert ctx.lineWidth === 1;
+
+    ctx.lineWidth = 1.5;
+    ctx.lineWidth = false;
+    @assert ctx.lineWidth === 1.5;
+
 - name: 2d.line.cap.butt
   desc: lineCap 'butt' is rendered correctly
   testing:
@@ -4512,6 +4524,18 @@
     ctx.miterLimit = NaN;
     @assert ctx.miterLimit === 1.5;
 
+    ctx.miterLimit = 1.5;
+    ctx.miterLimit = 'string';
+    @assert ctx.miterLimit === 1.5;
+
+    ctx.miterLimit = 1.5;
+    ctx.miterLimit = true;
+    @assert ctx.miterLimit === 1;
+
+    ctx.miterLimit = 1.5;
+    ctx.miterLimit = false;
+    @assert ctx.miterLimit === 1.5;
+
 - name: 2d.line.cross
   code: |
     ctx.fillStyle = '#0f0';
@@ -4607,6 +4631,18 @@
     ctx.shadowBlur = NaN;
     @assert ctx.shadowBlur === 1;
 
+    ctx.shadowBlur = 1;
+    ctx.shadowBlur = 'string';
+    @assert ctx.shadowBlur === 1;
+
+    ctx.shadowBlur = 1;
+    ctx.shadowBlur = true;
+    @assert ctx.shadowBlur === 1;
+
+    ctx.shadowBlur = 1;
+    ctx.shadowBlur = false;
+    @assert ctx.shadowBlur === 0;
+
 - name: 2d.shadow.attributes.shadowOffset.initial
   testing:
     - 2d.shadow.offset.initial
@@ -4669,6 +4705,27 @@
     @assert ctx.shadowOffsetX === 1;
     @assert ctx.shadowOffsetY === 2;
 
+    ctx.shadowOffsetX = 1;
+    ctx.shadowOffsetY = 2;
+    ctx.shadowOffsetX = 'string';
+    ctx.shadowOffsetY = 'string';
+    @assert ctx.shadowOffsetX === 1;
+    @assert ctx.shadowOffsetY === 2;
+
+    ctx.shadowOffsetX = 1;
+    ctx.shadowOffsetY = 2;
+    ctx.shadowOffsetX = true;
+    ctx.shadowOffsetY = true;
+    @assert ctx.shadowOffsetX === 1;
+    @assert ctx.shadowOffsetY === 1;
+
+    ctx.shadowOffsetX = 1;
+    ctx.shadowOffsetY = 2;
+    ctx.shadowOffsetX = false;
+    ctx.shadowOffsetY = false;
+    @assert ctx.shadowOffsetX === 0;
+    @assert ctx.shadowOffsetY === 0;
+
 - name: 2d.shadow.attributes.shadowColor.initial
   testing:
     - 2d.shadow.color.initial
@@ -9732,6 +9789,38 @@
   expected: green
 
 
+- name: 2d.imageData.get.large.crash
+  desc: Test that canvas crash when image data cannot be allocated.
+  testing:
+    - 2d.getImageData
+  code: |
+    @assert throws TypeError ctx.getImageData(10, 0xffffffff, 2147483647, 10);
+
+- name: 2d.imageData.get.rounding
+  desc: Test the handling of non-integer source coordinates in getImageData().
+  testing:
+    - 2d.getImageData
+  code: |
+    function testDimensions(sx, sy, sw, sh, width, height)
+    {
+        imageData = ctx.getImageData(sx, sy, sw, sh);
+        @assert imageData.width == width;
+        @assert imageData.height == height;
+    }
+
+    testDimensions(0, 0, 20, 10, 20, 10);
+
+    testDimensions(.1, .2, 20, 10, 20, 10);
+    testDimensions(.9, .8, 20, 10, 20, 10);
+
+    testDimensions(0, 0, 20.9, 10.9, 20, 10);
+    testDimensions(0, 0, 20.1, 10.1, 20, 10);
+
+    testDimensions(-1, -1, 20, 10, 20, 10);
+
+    testDimensions(-1.1, 0, 20, 10, 20, 10);
+    testDimensions(-1.9,  0, 20, 10, 20, 10);
+
 - name: 2d.imageData.object.properties
   desc: ImageData objects have the right properties
   testing:
@@ -10365,4 +10454,30 @@
     ctx.filter = 'blur(  5px)';
     assert_equals(ctx.filter, 'blur(  5px)');
 
+- name: 2d.line.invalid.strokestyle
+  desc: Verify correct behavior of canvas on an invalid strokeStyle()
+  testing:
+    - 2d.strokestyle.invalid
+  code: |
+    ctx.strokeStyle = 'rgb(0, 255, 0)';
+    ctx.strokeStyle = 'nonsense';
+    ctx.lineWidth = 200;
+    ctx.moveTo(0,100);
+    ctx.lineTo(200,100);
+    ctx.stroke();
+    var imageData = ctx.getImageData(0, 0, 200, 200);
+    var imgdata = imageData.data;
+    @assert imgdata[4] == 0;
+    @assert imgdata[5] == 255;
+    @assert imgdata[6] == 0;
 
+- name: 2d.video.invalid
+  desc: Verify test doesn't crash with invalid video.
+  testing:
+    - 2d.video.invalid
+  code: |
+    var v = document.createElement('video');
+    v.play();
+    // Test is deliberately not waiting for the 'playing' event to fire.
+    ctx.createPattern(v, 'repeat-x');
+    ctx.drawImage(v, 0, 0);
diff --git a/tests/wpt/web-platform-tests/2dcontext/video/2d.video.invalid.html b/tests/wpt/web-platform-tests/2dcontext/video/2d.video.invalid.html
new file mode 100644
index 00000000000..cba6dbcd6f0
--- /dev/null
+++ b/tests/wpt/web-platform-tests/2dcontext/video/2d.video.invalid.html
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<!-- DO NOT EDIT! This test has been generated by /2dcontext/tools/gentest.py. -->
+<title>Canvas test: 2d.video.invalid</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/2dcontext/resources/canvas-tests.js"></script>
+<link rel="stylesheet" href="/2dcontext/resources/canvas-tests.css">
+<body class="show_output">
+
+<h1>2d.video.invalid</h1>
+<p class="desc">Verify test doesn't crash with invalid video.</p>
+
+
+<p class="output">Actual output:</p>
+<canvas id="c" class="output" width="100" height="50"><p class="fallback">FAIL (fallback content)</p></canvas>
+
+<ul id="d"></ul>
+<script>
+var t = async_test("Verify test doesn't crash with invalid video.");
+_addTest(function(canvas, ctx) {
+
+var v = document.createElement('video');
+v.play();
+// Test is deliberately not waiting for the 'playing' event to fire.
+ctx.createPattern(v, 'repeat-x');
+ctx.drawImage(v, 0, 0);
+
+
+});
+</script>
+
diff --git a/tests/wpt/web-platform-tests/bluetooth/resources/bluetooth-fake-devices.js b/tests/wpt/web-platform-tests/bluetooth/resources/bluetooth-fake-devices.js
index 3bbcc6b322e..07c99cf65a5 100644
--- a/tests/wpt/web-platform-tests/bluetooth/resources/bluetooth-fake-devices.js
+++ b/tests/wpt/web-platform-tests/bluetooth/resources/bluetooth-fake-devices.js
@@ -195,20 +195,21 @@ function simulateGATTDisconnectionAndWait(device, fake_peripheral) {
  * @returns {Promise<Array<FakePeripheral>>} The fake devices are initialized as
  *     Health Thermometer and Heart Rate devices.
  */
-function setUpHealthThermometerAndHeartRateDevices() {
-  return navigator.bluetooth.test.simulateCentral({state: 'powered-on'})
-      .then(fake_central => Promise.all([
-        fake_central.simulatePreconnectedPeripheral({
-          address: '09:09:09:09:09:09',
-          name: 'Health Thermometer',
-          knownServiceUUIDs: ['generic_access', 'health_thermometer'],
-        }),
-        fake_central.simulatePreconnectedPeripheral({
-          address: '08:08:08:08:08:08',
-          name: 'Heart Rate',
-          knownServiceUUIDs: ['generic_access', 'heart_rate'],
-        })
-      ]));
+async function setUpHealthThermometerAndHeartRateDevices() {
+  let fake_central =
+      await navigator.bluetooth.test.simulateCentral({state: 'powered-on'});
+  return Promise.all([
+    fake_central.simulatePreconnectedPeripheral({
+      address: '09:09:09:09:09:09',
+      name: 'Health Thermometer',
+      knownServiceUUIDs: ['generic_access', 'health_thermometer'],
+    }),
+    fake_central.simulatePreconnectedPeripheral({
+      address: '08:08:08:08:08:08',
+      name: 'Heart Rate',
+      knownServiceUUIDs: ['generic_access', 'heart_rate'],
+    })
+  ]);
 }
 
 /**
@@ -221,17 +222,18 @@ function setUpHealthThermometerAndHeartRateDevices() {
  * @returns {Promise<FakePeripheral>} The fake devices are initialized with the
  *     parameter values.
  */
-function setUpPreconnectedDevice({
+async function setUpPreconnectedDevice({
   address = '00:00:00:00:00:00',
   name = 'LE Device',
   knownServiceUUIDs = []
 }) {
-  return navigator.bluetooth.test.simulateCentral({state: 'powered-on'})
-      .then(fake_central => fake_central.simulatePreconnectedPeripheral({
-        address: address,
-        name: name,
-        knownServiceUUIDs: knownServiceUUIDs,
-      }));
+  let fake_central =
+      await navigator.bluetooth.test.simulateCentral({state: 'powered-on'})
+  return fake_central.simulatePreconnectedPeripheral({
+    address: address,
+    name: name,
+    knownServiceUUIDs: knownServiceUUIDs,
+  });
 }
 
 /** Blocklisted GATT Device Helper Methods */
@@ -266,65 +268,52 @@ function setUpPreconnectedDevice({
  *         object containing the BluetoothDevice object and its corresponding
  *         GATT fake objects.
  */
-function getBlocklistDevice(options = {
+async function getBlocklistDevice(options = {
   filters: [{services: [blocklist_test_service_uuid]}]
 }) {
-  let device, fake_peripheral, fake_blocklist_test_service,
-      fake_blocklist_exclude_reads_characteristic,
-      fake_blocklist_exclude_writes_characteristic, fake_blocklist_descriptor,
-      fake_blocklist_exclude_reads_descriptor,
-      fake_blocklist_exclude_writes_descriptor;
-  return setUpPreconnectedDevice({
-           address: '11:11:11:11:11:11',
-           name: 'Blocklist Device',
-           knownServiceUUIDs: ['generic_access', blocklist_test_service_uuid],
-         })
-      .then(_ => fake_peripheral = _)
-      .then(() => requestDeviceWithTrustedClick(options))
-      .then(_ => device = _)
-      .then(() => fake_peripheral.setNextGATTConnectionResponse({
-        code: HCI_SUCCESS,
-      }))
-      .then(() => device.gatt.connect())
-      .then(() => fake_peripheral.addFakeService({
-        uuid: blocklist_test_service_uuid,
-      }))
-      .then(_ => fake_blocklist_test_service = _)
-      .then(() => fake_blocklist_test_service.addFakeCharacteristic({
+  let fake_peripheral = await setUpPreconnectedDevice({
+    address: '11:11:11:11:11:11',
+    name: 'Blocklist Device',
+    knownServiceUUIDs: ['generic_access', blocklist_test_service_uuid],
+  })
+  let device = await requestDeviceWithTrustedClick(options);
+  await fake_peripheral.setNextGATTConnectionResponse({
+    code: HCI_SUCCESS,
+  });
+  await device.gatt.connect();
+  let fake_blocklist_test_service = await fake_peripheral.addFakeService({
+    uuid: blocklist_test_service_uuid,
+  });
+  let fake_blocklist_exclude_reads_characteristic =
+      await fake_blocklist_test_service.addFakeCharacteristic({
         uuid: blocklist_exclude_reads_characteristic_uuid,
         properties: ['read', 'write'],
-      }))
-      .then(_ => fake_blocklist_exclude_reads_characteristic = _)
-      .then(() => fake_blocklist_test_service.addFakeCharacteristic({
+      });
+  let fake_blocklist_exclude_writes_characteristic =
+      await fake_blocklist_test_service.addFakeCharacteristic({
         uuid: 'gap.peripheral_privacy_flag',
         properties: ['read', 'write'],
-      }))
-      .then(_ => fake_blocklist_exclude_writes_characteristic = _)
-      .then(
-          () => fake_blocklist_exclude_writes_characteristic.addFakeDescriptor(
-              {uuid: blocklist_test_descriptor_uuid}))
-      .then(_ => fake_blocklist_descriptor = _)
-      .then(
-          () => fake_blocklist_exclude_writes_characteristic.addFakeDescriptor(
-              {uuid: blocklist_exclude_reads_descriptor_uuid}))
-      .then(_ => fake_blocklist_exclude_reads_descriptor = _)
-      .then(
-          () => fake_blocklist_exclude_writes_characteristic.addFakeDescriptor(
-              {uuid: 'gatt.client_characteristic_configuration'}))
-      .then(_ => fake_blocklist_exclude_writes_descriptor = _)
-      .then(() => fake_peripheral.setNextGATTDiscoveryResponse({
-        code: HCI_SUCCESS,
-      }))
-      .then(() => ({
-              device,
-              fake_peripheral,
-              fake_blocklist_test_service,
-              fake_blocklist_exclude_reads_characteristic,
-              fake_blocklist_exclude_writes_characteristic,
-              fake_blocklist_descriptor,
-              fake_blocklist_exclude_reads_descriptor,
-              fake_blocklist_exclude_writes_descriptor,
-            }));
+      });
+  let fake_blocklist_descriptor =
+      await fake_blocklist_exclude_writes_characteristic.addFakeDescriptor(
+          {uuid: blocklist_test_descriptor_uuid});
+  let fake_blocklist_exclude_reads_descriptor =
+      await fake_blocklist_exclude_writes_characteristic.addFakeDescriptor(
+          {uuid: blocklist_exclude_reads_descriptor_uuid});
+  let fake_blocklist_exclude_writes_descriptor =
+      await fake_blocklist_exclude_writes_characteristic.addFakeDescriptor(
+          {uuid: 'gatt.client_characteristic_configuration'});
+  await fake_peripheral.setNextGATTDiscoveryResponse({code: HCI_SUCCESS});
+  return {
+    device,
+    fake_peripheral,
+    fake_blocklist_test_service,
+    fake_blocklist_exclude_reads_characteristic,
+    fake_blocklist_exclude_writes_characteristic,
+    fake_blocklist_descriptor,
+    fake_blocklist_exclude_reads_descriptor,
+    fake_blocklist_exclude_writes_descriptor,
+  };
 }
 
 /**
@@ -343,17 +332,14 @@ function getBlocklistDevice(options = {
  *     fake_service: FakeBluetoothRemoteGATTService}>} An object containing the
  *         BluetoothDevice object and its corresponding GATT fake objects.
  */
-function getBlocklistTestService() {
-  let result;
-  return getBlocklistDevice()
-      .then(_ => result = _)
-      .then(
-          () =>
-              result.device.gatt.getPrimaryService(blocklist_test_service_uuid))
-      .then(service => Object.assign(result, {
-        service,
-        fake_service: result.fake_blocklist_test_service,
-      }));
+async function getBlocklistTestService() {
+  let result = await getBlocklistDevice();
+  let service =
+      await result.device.gatt.getPrimaryService(blocklist_test_service_uuid);
+  return Object.assign(result, {
+    service,
+    fake_service: result.fake_blocklist_test_service,
+  });
 }
 
 /**
@@ -375,17 +361,14 @@ function getBlocklistTestService() {
  *         containing the BluetoothDevice object and its corresponding GATT fake
  *         objects.
  */
-function getBlocklistExcludeReadsCharacteristic() {
-  let result, fake_characteristic;
-  return getBlocklistTestService()
-      .then(_ => result = _)
-      .then(
-          () => result.service.getCharacteristic(
-              blocklist_exclude_reads_characteristic_uuid))
-      .then(characteristic => Object.assign(result, {
-        characteristic,
-        fake_characteristic: result.fake_blocklist_exclude_reads_characteristic
-      }));
+async function getBlocklistExcludeReadsCharacteristic() {
+  let result = await getBlocklistTestService();
+  let characteristic = await result.service.getCharacteristic(
+      blocklist_exclude_reads_characteristic_uuid);
+  return Object.assign(result, {
+    characteristic,
+    fake_characteristic: result.fake_blocklist_exclude_reads_characteristic
+  });
 }
 
 /**
@@ -407,16 +390,14 @@ function getBlocklistExcludeReadsCharacteristic() {
  *         containing the BluetoothDevice object and its corresponding GATT fake
  *         objects.
  */
-function getBlocklistExcludeWritesCharacteristic() {
-  let result, fake_characteristic;
-  return getBlocklistTestService()
-      .then(_ => result = _)
-      .then(
-          () => result.service.getCharacteristic('gap.peripheral_privacy_flag'))
-      .then(characteristic => Object.assign(result, {
-        characteristic,
-        fake_characteristic: result.fake_blocklist_exclude_writes_characteristic
-      }));
+async function getBlocklistExcludeWritesCharacteristic() {
+  let result = await getBlocklistTestService();
+  let characteristic =
+      await result.service.getCharacteristic('gap.peripheral_privacy_flag');
+  return Object.assign(result, {
+    characteristic,
+    fake_characteristic: result.fake_blocklist_exclude_writes_characteristic
+  });
 }
 
 /**
@@ -440,17 +421,14 @@ function getBlocklistExcludeWritesCharacteristic() {
  *         containing the BluetoothDevice object and its corresponding GATT fake
  *         objects.
  */
-function getBlocklistExcludeReadsDescriptor() {
-  let result;
-  return getBlocklistExcludeWritesCharacteristic()
-      .then(_ => result = _)
-      .then(
-          () => result.characteristic.getDescriptor(
-              blocklist_exclude_reads_descriptor_uuid))
-      .then(descriptor => Object.assign(result, {
-        descriptor,
-        fake_descriptor: result.fake_blocklist_exclude_reads_descriptor
-      }));
+async function getBlocklistExcludeReadsDescriptor() {
+  let result = await getBlocklistExcludeWritesCharacteristic();
+  let descriptor = await result.characteristic.getDescriptor(
+      blocklist_exclude_reads_descriptor_uuid);
+  return Object.assign(result, {
+    descriptor,
+    fake_descriptor: result.fake_blocklist_exclude_reads_descriptor
+  });
 }
 
 /**
@@ -474,17 +452,14 @@ function getBlocklistExcludeReadsDescriptor() {
  *         containing the BluetoothDevice object and its corresponding GATT fake
  *         objects.
  */
-function getBlocklistExcludeWritesDescriptor() {
-  let result;
-  return getBlocklistExcludeWritesCharacteristic()
-      .then(_ => result = _)
-      .then(
-          () => result.characteristic.getDescriptor(
-              'gatt.client_characteristic_configuration'))
-      .then(descriptor => Object.assign(result, {
-        descriptor: descriptor,
-        fake_descriptor: result.fake_blocklist_exclude_writes_descriptor,
-      }));
+async function getBlocklistExcludeWritesDescriptor() {
+  let result = await getBlocklistExcludeWritesCharacteristic();
+  let descriptor = await result.characteristic.getDescriptor(
+      'gatt.client_characteristic_configuration');
+  return Object.assign(result, {
+    descriptor: descriptor,
+    fake_descriptor: result.fake_blocklist_exclude_writes_descriptor,
+  });
 }
 
 /** Bluetooth HID Device Helper Methods */
@@ -498,40 +473,37 @@ function getBlocklistExcludeWritesDescriptor() {
  * @returns {device: BluetoothDevice, fake_peripheral: FakePeripheral} An object
  *     containing a requested BluetoothDevice and its fake counter part.
  */
-function getConnectedHIDDevice(options) {
-  let device, fake_peripheral;
-  return setUpPreconnectedDevice({
-           address: '10:10:10:10:10:10',
-           name: 'HID Device',
-           knownServiceUUIDs: [
-             'generic_access',
-             'device_information',
-             'human_interface_device',
-           ],
-         })
-      .then(_ => (fake_peripheral = _))
-      .then(() => requestDeviceWithTrustedClick(options))
-      .then(_ => (device = _))
-      .then(() => fake_peripheral.setNextGATTConnectionResponse({
-        code: HCI_SUCCESS,
-      }))
-      .then(() => device.gatt.connect())
-      .then(() => fake_peripheral.addFakeService({
-        uuid: 'generic_access',
-      }))
-      .then(() => fake_peripheral.addFakeService({
-        uuid: 'device_information',
-      }))
-      // Blocklisted Characteristic:
-      // https://github.com/WebBluetoothCG/registries/blob/master/gatt_blocklist.txt
-      .then(dev_info => dev_info.addFakeCharacteristic({
-        uuid: 'serial_number_string',
-        properties: ['read'],
-      }))
-      .then(() => fake_peripheral.addFakeService({
-        uuid: 'human_interface_device',
-      }))
-      .then(() => ({device, fake_peripheral}));
+async function getConnectedHIDDevice(options) {
+  let fake_peripheral = await setUpPreconnectedDevice({
+    address: '10:10:10:10:10:10',
+    name: 'HID Device',
+    knownServiceUUIDs: [
+      'generic_access',
+      'device_information',
+      'human_interface_device',
+    ],
+  });
+  let device = await requestDeviceWithTrustedClick(options);
+  await fake_peripheral.setNextGATTConnectionResponse({
+    code: HCI_SUCCESS,
+  });
+  await device.gatt.connect();
+  await fake_peripheral.addFakeService({
+    uuid: 'generic_access',
+  });
+  let dev_info = await fake_peripheral.addFakeService({
+    uuid: 'device_information',
+  });
+  // Blocklisted Characteristic:
+  // https://github.com/WebBluetoothCG/registries/blob/master/gatt_blocklist.txt
+  await dev_info.addFakeCharacteristic({
+    uuid: 'serial_number_string',
+    properties: ['read'],
+  });
+  await fake_peripheral.addFakeService({
+    uuid: 'human_interface_device',
+  });
+  return {device, fake_peripheral};
 }
 
 /**
@@ -547,14 +519,12 @@ function getConnectedHIDDevice(options) {
  * @returns {device: BluetoothDevice, fake_peripheral: FakePeripheral} An object
  *     containing a requested BluetoothDevice and its fake counter part.
  */
-function getHIDDevice(options) {
-  let device, fake_peripheral;
-  return getConnectedHIDDevice(options)
-      .then(_ => ({device, fake_peripheral} = _))
-      .then(() => fake_peripheral.setNextGATTDiscoveryResponse({
-        code: HCI_SUCCESS,
-      }))
-      .then(() => ({device, fake_peripheral}));
+async function getHIDDevice(options) {
+  let result = await getConnectedHIDDevice(options);
+  await result.fake_peripheral.setNextGATTDiscoveryResponse({
+    code: HCI_SUCCESS,
+  });
+  return result;
 }
 
 /** Health Thermometer Bluetooth Device Helper Methods */
@@ -563,7 +533,7 @@ function getHIDDevice(options) {
  * Returns a FakePeripheral that corresponds to a simulated pre-connected device
  * called 'Health Thermometer'. The device has two known serviceUUIDs:
  * 'generic_access' and 'health_thermometer'.
- * @returns {FakePeripheral} The device fake initialized as a Health
+ * @returns {Promise<FakePeripheral>} The device fake initialized as a Health
  *     Thermometer device.
  */
 function setUpHealthThermometerDevice() {
@@ -580,14 +550,12 @@ function setUpHealthThermometerDevice() {
  * @returns {Promise<FakePeripheral>} The device fake initialized as a
  *     connectable Health Thermometer device.
  */
-function setUpConnectableHealthThermometerDevice() {
-  let fake_peripheral;
-  return setUpHealthThermometerDevice()
-      .then(_ => fake_peripheral = _)
-      .then(() => fake_peripheral.setNextGATTConnectionResponse({
-        code: HCI_SUCCESS,
-      }))
-      .then(() => fake_peripheral);
+async function setUpConnectableHealthThermometerDevice() {
+  let fake_peripheral = await setUpHealthThermometerDevice();
+  await fake_peripheral.setNextGATTConnectionResponse({
+    code: HCI_SUCCESS,
+  });
+  return fake_peripheral;
 }
 
 /**
@@ -607,49 +575,44 @@ function setUpConnectableHealthThermometerDevice() {
  * passed into this method along with the fake GATT services, characteristics,
  *         and descriptors added to it.
  */
-function populateHealthThermometerFakes(fake_peripheral) {
-  let fake_generic_access, fake_health_thermometer, fake_measurement_interval,
-      fake_user_description, fake_cccd, fake_temperature_measurement,
-      fake_temperature_type;
-  return fake_peripheral.addFakeService({uuid: 'generic_access'})
-      .then(_ => fake_generic_access = _)
-      .then(() => fake_peripheral.addFakeService({
-        uuid: 'health_thermometer',
-      }))
-      .then(_ => fake_health_thermometer = _)
-      .then(() => fake_health_thermometer.addFakeCharacteristic({
+async function populateHealthThermometerFakes(fake_peripheral) {
+  let fake_generic_access =
+      await fake_peripheral.addFakeService({uuid: 'generic_access'});
+  let fake_health_thermometer = await fake_peripheral.addFakeService({
+    uuid: 'health_thermometer',
+  });
+  let fake_measurement_interval =
+      await fake_health_thermometer.addFakeCharacteristic({
         uuid: 'measurement_interval',
         properties: ['read', 'write', 'indicate'],
-      }))
-      .then(_ => fake_measurement_interval = _)
-      .then(() => fake_measurement_interval.addFakeDescriptor({
+      });
+  let fake_user_description =
+      await fake_measurement_interval.addFakeDescriptor({
         uuid: 'gatt.characteristic_user_description',
-      }))
-      .then(_ => fake_user_description = _)
-      .then(() => fake_measurement_interval.addFakeDescriptor({
-        uuid: 'gatt.client_characteristic_configuration',
-      }))
-      .then(_ => fake_cccd = _)
-      .then(() => fake_health_thermometer.addFakeCharacteristic({
+      });
+  let fake_cccd = await fake_measurement_interval.addFakeDescriptor({
+    uuid: 'gatt.client_characteristic_configuration',
+  });
+  let fake_temperature_measurement =
+      await fake_health_thermometer.addFakeCharacteristic({
         uuid: 'temperature_measurement',
         properties: ['indicate'],
-      }))
-      .then(_ => fake_temperature_measurement = _)
-      .then(() => fake_health_thermometer.addFakeCharacteristic({
+      });
+  let fake_temperature_type =
+      await fake_health_thermometer.addFakeCharacteristic({
         uuid: 'temperature_type',
         properties: ['read'],
-      }))
-      .then(_ => fake_temperature_type = _)
-      .then(() => ({
-              fake_peripheral,
-              fake_generic_access,
-              fake_health_thermometer,
-              fake_measurement_interval,
-              fake_cccd,
-              fake_user_description,
-              fake_temperature_measurement,
-              fake_temperature_type,
-            }));
+      });
+  return {
+    fake_peripheral,
+    fake_generic_access,
+    fake_health_thermometer,
+    fake_measurement_interval,
+    fake_cccd,
+    fake_user_description,
+    fake_temperature_measurement,
+    fake_temperature_type,
+  };
 }
 
 /**
@@ -670,50 +633,45 @@ function populateHealthThermometerFakes(fake_peripheral) {
  *         containing a requested BluetoothDevice and all of the GATT fake
  *         objects.
  */
-function getHealthThermometerDeviceWithServicesDiscovered(options) {
-  let device, fake_peripheral, fakes;
+async function getHealthThermometerDeviceWithServicesDiscovered(options) {
   let iframe = document.createElement('iframe');
-  return setUpConnectableHealthThermometerDevice()
-      .then(_ => fake_peripheral = _)
-      .then(() => populateHealthThermometerFakes(fake_peripheral))
-      .then(_ => fakes = _)
-      .then(() => fake_peripheral.setNextGATTDiscoveryResponse({
-        code: HCI_SUCCESS,
-      }))
-      .then(
-          () => new Promise(resolve => {
-            let src = '/bluetooth/resources/health-thermometer-iframe.html';
-            // TODO(509038): Can be removed once LayoutTests/bluetooth/* that
-            // use health-thermometer-iframe.html have been moved to
-            // LayoutTests/external/wpt/bluetooth/*
-            if (window.location.pathname.includes('/LayoutTests/')) {
-              src =
-                  '../../../external/wpt/bluetooth/resources/health-thermometer-iframe.html';
-            }
-            iframe.src = src;
-            document.body.appendChild(iframe);
-            iframe.addEventListener('load', resolve);
-          }))
-      .then(() => new Promise((resolve, reject) => {
-              callWithTrustedClick(() => {
-                iframe.contentWindow.postMessage(
-                    {type: 'DiscoverServices', options: options}, '*');
-              });
+  let fake_peripheral = await setUpConnectableHealthThermometerDevice();
+  let fakes = populateHealthThermometerFakes(fake_peripheral);
+  await fake_peripheral.setNextGATTDiscoveryResponse({
+    code: HCI_SUCCESS,
+  });
+  await new Promise(resolve => {
+    let src = '/bluetooth/resources/health-thermometer-iframe.html';
+    // TODO(509038): Can be removed once LayoutTests/bluetooth/* that
+    // use health-thermometer-iframe.html have been moved to
+    // LayoutTests/external/wpt/bluetooth/*
+    if (window.location.pathname.includes('/LayoutTests/')) {
+      src =
+          '../../../external/wpt/bluetooth/resources/health-thermometer-iframe.html';
+    }
+    iframe.src = src;
+    document.body.appendChild(iframe);
+    iframe.addEventListener('load', resolve);
+  });
+  await new Promise((resolve, reject) => {
+    callWithTrustedClick(() => {
+      iframe.contentWindow.postMessage(
+          {type: 'DiscoverServices', options: options}, '*');
+    });
 
-              function messageHandler(messageEvent) {
-                if (messageEvent.data == 'DiscoveryComplete') {
-                  window.removeEventListener('message', messageHandler);
-                  resolve();
-                } else {
-                  reject(new Error(`Unexpected message: ${messageEvent.data}`));
-                }
-              }
-              window.addEventListener('message', messageHandler);
-            }))
-      .then(() => requestDeviceWithTrustedClick(options))
-      .then(_ => device = _)
-      .then(device => device.gatt.connect())
-      .then(_ => Object.assign({device}, fakes));
+    function messageHandler(messageEvent) {
+      if (messageEvent.data == 'DiscoveryComplete') {
+        window.removeEventListener('message', messageHandler);
+        resolve();
+      } else {
+        reject(new Error(`Unexpected message: ${messageEvent.data}`));
+      }
+    }
+    window.addEventListener('message', messageHandler);
+  });
+  let device = await requestDeviceWithTrustedClick(options);
+  await device.gatt.connect();
+  return Object.assign({device}, fakes);
 }
 
 /**
@@ -725,13 +683,12 @@ function getHealthThermometerDeviceWithServicesDiscovered(options) {
  * @returns {device: BluetoothDevice, fake_peripheral: FakePeripheral} An object
  *     containing a requested BluetoothDevice and its fake counter part.
  */
-function getDiscoveredHealthThermometerDevice(options = {
+async function getDiscoveredHealthThermometerDevice(options = {
   filters: [{services: ['health_thermometer']}]
 }) {
-  return setUpHealthThermometerDevice().then(fake_peripheral => {
-    return requestDeviceWithTrustedClick(options).then(
-        device => ({device: device, fake_peripheral: fake_peripheral}));
-  });
+  let fake_peripheral = await setUpHealthThermometerDevice();
+  let device = await requestDeviceWithTrustedClick(options);
+  return {device: device, fake_peripheral: fake_peripheral};
 }
 
 /**
@@ -742,17 +699,14 @@ function getDiscoveredHealthThermometerDevice(options = {
  * @returns {device: BluetoothDevice, fake_peripheral: FakePeripheral} An object
  *     containing a requested BluetoothDevice and its fake counter part.
  */
-function getEmptyHealthThermometerDevice(options) {
-  return getDiscoveredHealthThermometerDevice(options).then(
-      ({device, fake_peripheral}) => {
-        return fake_peripheral
-            .setNextGATTConnectionResponse({code: HCI_SUCCESS})
-            .then(() => device.gatt.connect())
-            .then(
-                () => fake_peripheral.setNextGATTDiscoveryResponse(
-                    {code: HCI_SUCCESS}))
-            .then(() => ({device: device, fake_peripheral: fake_peripheral}));
-      });
+async function getEmptyHealthThermometerDevice(options) {
+  let result = await getDiscoveredHealthThermometerDevice(options);
+  await result.fake_peripheral.setNextGATTConnectionResponse(
+      {code: HCI_SUCCESS});
+  await result.device.gatt.connect();
+  await result.fake_peripheral.setNextGATTDiscoveryResponse(
+      {code: HCI_SUCCESS});
+  return result;
 }
 
 /**
@@ -764,26 +718,21 @@ function getEmptyHealthThermometerDevice(options) {
  *     fake_health_thermometer: FakeRemoteGATTService} An object containing the
  * health themometer service object and its corresponding fake.
  */
-function getEmptyHealthThermometerService(options) {
-  let device;
-  let fake_peripheral;
-  let fake_health_thermometer;
-  return getDiscoveredHealthThermometerDevice(options)
-      .then(result => ({device, fake_peripheral} = result))
-      .then(
-          () => fake_peripheral.setNextGATTConnectionResponse(
-              {code: HCI_SUCCESS}))
-      .then(() => device.gatt.connect())
-      .then(() => fake_peripheral.addFakeService({uuid: 'health_thermometer'}))
-      .then(s => fake_health_thermometer = s)
-      .then(
-          () =>
-              fake_peripheral.setNextGATTDiscoveryResponse({code: HCI_SUCCESS}))
-      .then(() => device.gatt.getPrimaryService('health_thermometer'))
-      .then(service => ({
-              service: service,
-              fake_health_thermometer: fake_health_thermometer,
-            }));
+async function getEmptyHealthThermometerService(options) {
+  let result = await getDiscoveredHealthThermometerDevice(options);
+  await result.fake_peripheral.setNextGATTConnectionResponse(
+      {code: HCI_SUCCESS});
+  await result.device.gatt.connect();
+  let fake_health_thermometer =
+      await result.fake_peripheral.addFakeService({uuid: 'health_thermometer'});
+  await result.fake_peripheral.setNextGATTDiscoveryResponse(
+      {code: HCI_SUCCESS});
+  let service =
+      await result.device.gatt.getPrimaryService('health_thermometer');
+  return {
+    service: service,
+    fake_health_thermometer: fake_health_thermometer,
+  };
 }
 
 /**
@@ -803,17 +752,14 @@ function getEmptyHealthThermometerService(options) {
  *         containing a requested BluetoothDevice and all of the GATT fake
  *         objects.
  */
-function getConnectedHealthThermometerDevice(options) {
-  let device, fake_peripheral, fakes;
-  return getDiscoveredHealthThermometerDevice(options)
-      .then(_ => ({device, fake_peripheral} = _))
-      .then(() => fake_peripheral.setNextGATTConnectionResponse({
-        code: HCI_SUCCESS,
-      }))
-      .then(() => populateHealthThermometerFakes(fake_peripheral))
-      .then(_ => fakes = _)
-      .then(() => device.gatt.connect())
-      .then(() => Object.assign({device}, fakes));
+async function getConnectedHealthThermometerDevice(options) {
+  let result = await getDiscoveredHealthThermometerDevice(options);
+  await result.fake_peripheral.setNextGATTConnectionResponse({
+    code: HCI_SUCCESS,
+  });
+  let fakes = await populateHealthThermometerFakes(result.fake_peripheral);
+  await result.device.gatt.connect();
+  return Object.assign({device: result.device}, fakes);
 }
 
 /**
@@ -845,14 +791,12 @@ function getConnectedHealthThermometerDevice(options) {
  *         containing a requested BluetoothDevice and all of the GATT fake
  *         objects.
  */
-function getHealthThermometerDevice(options) {
-  let result;
-  return getConnectedHealthThermometerDevice(options)
-      .then(_ => result = _)
-      .then(() => result.fake_peripheral.setNextGATTDiscoveryResponse({
-        code: HCI_SUCCESS,
-      }))
-      .then(() => result);
+async function getHealthThermometerDevice(options) {
+  let result = await getConnectedHealthThermometerDevice(options);
+  await result.fake_peripheral.setNextGATTDiscoveryResponse({
+    code: HCI_SUCCESS,
+  });
+  return result;
 }
 
 /**
@@ -866,34 +810,19 @@ function getHealthThermometerDevice(options) {
  * object containing a requested Bluetooth device and two fake health
  * thermometer GATT services.
  */
-function getTwoHealthThermometerServicesDevice(options) {
-  let device;
-  let fake_peripheral;
-  let fake_generic_access;
-  let fake_health_thermometer1;
-  let fake_health_thermometer2;
-
-  return getConnectedHealthThermometerDevice(options)
-      .then(result => {
-        ({
-          device,
-          fake_peripheral,
-          fake_generic_access,
-          fake_health_thermometer: fake_health_thermometer1,
-        } = result);
-      })
-      .then(() => fake_peripheral.addFakeService({uuid: 'health_thermometer'}))
-      .then(s => fake_health_thermometer2 = s)
-      .then(
-          () =>
-              fake_peripheral.setNextGATTDiscoveryResponse({code: HCI_SUCCESS}))
-      .then(() => ({
-              device: device,
-              fake_peripheral: fake_peripheral,
-              fake_generic_access: fake_generic_access,
-              fake_health_thermometer1: fake_health_thermometer1,
-              fake_health_thermometer2: fake_health_thermometer2
-            }));
+async function getTwoHealthThermometerServicesDevice(options) {
+  let result = await getConnectedHealthThermometerDevice(options);
+  let fake_health_thermometer2 =
+      await result.fake_peripheral.addFakeService({uuid: 'health_thermometer'});
+  await result.fake_peripheral.setNextGATTDiscoveryResponse(
+      {code: HCI_SUCCESS});
+  return {
+    device: result.device,
+    fake_peripheral: result.fake_peripheral,
+    fake_generic_access: result.fake_generic_access,
+    fake_health_thermometer1: result.fake_health_thermometer,
+    fake_health_thermometer2: fake_health_thermometer2
+  };
 }
 
 /**
@@ -913,15 +842,14 @@ function getTwoHealthThermometerServicesDevice(options) {
  *         containing a requested BluetoothDevice and all of the GATT fake
  *         objects.
  */
-function getHealthThermometerService() {
-  let result;
-  return getHealthThermometerDevice()
-      .then(r => result = r)
-      .then(() => result.device.gatt.getPrimaryService('health_thermometer'))
-      .then(service => Object.assign(result, {
-        service,
-        fake_service: result.fake_health_thermometer,
-      }));
+async function getHealthThermometerService() {
+  let result = await getHealthThermometerDevice();
+  let service =
+      await result.device.gatt.getPrimaryService('health_thermometer');
+  return Object.assign(result, {
+    service,
+    fake_service: result.fake_health_thermometer,
+  });
 }
 
 /**
@@ -944,15 +872,14 @@ function getHealthThermometerService() {
  *         containing a requested BluetoothDevice and all of the GATT fake
  *         objects.
  */
-function getMeasurementIntervalCharacteristic() {
-  let result;
-  return getHealthThermometerService()
-      .then(r => result = r)
-      .then(() => result.service.getCharacteristic('measurement_interval'))
-      .then(characteristic => Object.assign(result, {
-        characteristic,
-        fake_characteristic: result.fake_measurement_interval,
-      }));
+async function getMeasurementIntervalCharacteristic() {
+  let result = await getHealthThermometerService();
+  let characteristic =
+      await result.service.getCharacteristic('measurement_interval');
+  return Object.assign(result, {
+    characteristic,
+    fake_characteristic: result.fake_measurement_interval,
+  });
 }
 
 /**
@@ -977,15 +904,12 @@ function getMeasurementIntervalCharacteristic() {
  *         containing a requested BluetoothDevice and all of the GATT fake
  *         objects.
  */
-function getUserDescriptionDescriptor() {
-  let result;
-  return getMeasurementIntervalCharacteristic()
-      .then(r => result = r)
-      .then(
-          () => result.characteristic.getDescriptor(
-              'gatt.characteristic_user_description'))
-      .then(descriptor => Object.assign(result, {
-        descriptor,
-        fake_descriptor: result.fake_user_description,
-      }));
+async function getUserDescriptionDescriptor() {
+  let result = await getMeasurementIntervalCharacteristic();
+  let descriptor = await result.characteristic.getDescriptor(
+      'gatt.characteristic_user_description');
+  return Object.assign(result, {
+    descriptor,
+    fake_descriptor: result.fake_user_description,
+  });
 }
diff --git a/tests/wpt/web-platform-tests/bluetooth/resources/bluetooth-test.js b/tests/wpt/web-platform-tests/bluetooth/resources/bluetooth-test.js
index d2c6bcbdb73..01cabe89bb6 100644
--- a/tests/wpt/web-platform-tests/bluetooth/resources/bluetooth-test.js
+++ b/tests/wpt/web-platform-tests/bluetooth/resources/bluetooth-test.js
@@ -24,12 +24,11 @@ function loadScript(path) {
  * @returns {Promise<void>} A promise chain that resolves when all scripts have
  *     finished loading.
  */
-function loadScripts(paths) {
-  let chain = Promise.resolve();
+async function loadScripts(paths) {
   for (let path of paths) {
-    chain = chain.then(() => loadScript(path));
+    await loadScript(path);
   }
-  return chain;
+  return;
 }
 
 /**
@@ -42,7 +41,7 @@ function loadScripts(paths) {
  * Bluetooth Blink Web Tests have been migrated into this repository.
  * @returns {Promise<void>} Resolves when Chromium specific setup is complete.
  */
-function performChromiumSetup() {
+async function performChromiumSetup() {
   // Make sure we are actually on Chromium with Mojo enabled.
   if (typeof Mojo === 'undefined') {
     return;
@@ -65,27 +64,26 @@ function performChromiumSetup() {
       '/js-test-resources/bluetooth/bluetooth-fake-adapter.js',
     ];
   }
-  return loadScripts([
-           `${genPrefix}/layout_test_data/mojo/public/js/mojo_bindings.js`,
-           `${genPrefix}/content/test/data/mojo_web_test_helper_test.mojom.js`,
-           `${genPrefix}/device/bluetooth/public/mojom/uuid.mojom.js`,
-           `${genPrefix}/url/mojom/origin.mojom.js`,
-           `${genPrefix}/device/bluetooth/public/mojom/test/fake_bluetooth.mojom.js`,
-           `${genPrefix}/content/shell/common/web_test/fake_bluetooth_chooser.mojom.js`,
-           `${prefix}/web-bluetooth-test.js`,
-         ].concat(extra))
-      // Call setBluetoothFakeAdapter() to clean up any fake adapters left over
-      // by legacy tests.
-      // Legacy tests that use setBluetoothFakeAdapter() sometimes fail to clean
-      // their fake adapter. This is not a problem for these tests because the
-      // next setBluetoothFakeAdapter() will clean it up anyway but it is a
-      // problem for the new tests that do not use setBluetoothFakeAdapter().
-      // TODO(https://crbug.com/569709): Remove once setBluetoothFakeAdapter is
-      // no longer used.
-      .then(
-          () => typeof setBluetoothFakeAdapter === 'undefined' ?
-              undefined :
-              setBluetoothFakeAdapter(''));
+  await loadScripts([
+    `${genPrefix}/layout_test_data/mojo/public/js/mojo_bindings.js`,
+    `${genPrefix}/content/test/data/mojo_web_test_helper_test.mojom.js`,
+    `${genPrefix}/device/bluetooth/public/mojom/uuid.mojom.js`,
+    `${genPrefix}/url/mojom/origin.mojom.js`,
+    `${genPrefix}/device/bluetooth/public/mojom/test/fake_bluetooth.mojom.js`,
+    `${genPrefix}/content/shell/common/web_test/fake_bluetooth_chooser.mojom.js`,
+    `${prefix}/web-bluetooth-test.js`,
+  ].concat(extra));
+
+  // Call setBluetoothFakeAdapter() to clean up any fake adapters left over by
+  // legacy tests. Legacy tests that use setBluetoothFakeAdapter() sometimes
+  // fail to clean their fake adapter. This is not a problem for these tests
+  // because the next setBluetoothFakeAdapter() will clean it up anyway but it
+  // is a problem for the new tests that do not use setBluetoothFakeAdapter().
+  // TODO(https://crbug.com/569709): Remove once setBluetoothFakeAdapter is no
+  // longer used.
+  if (typeof setBluetoothFakeAdapter !== 'undefined') {
+    setBluetoothFakeAdapter('');
+  }
 }
 
 /**
@@ -99,16 +97,13 @@ function performChromiumSetup() {
  *     rejects if the test failed.
  */
 function bluetooth_test(test_function, name, properties) {
-  Promise.resolve().then(
-      () => promise_test(
-          t => Promise
-                   .resolve()
-                   // Trigger Chromium-specific setup.
-                   .then(performChromiumSetup)
-                   .then(() => test_function(t))
-                   .then(() => navigator.bluetooth.test.allResponsesConsumed())
-                   .then(consumed => assert_true(consumed)),
-          name, properties));
+  return promise_test(async (t) => {
+    // Trigger Chromium-specific setup.
+    await performChromiumSetup();
+    await test_function(t);
+    let consumed = await navigator.bluetooth.test.allResponsesConsumed();
+    assert_true(consumed);
+  }, name, properties);
 }
 
 /**
@@ -138,22 +133,21 @@ function waitForDocumentReady() {
  * @returns {Promise<*>} Resolves when the user activation has been simulated
  *     with the result of |callback|.
  */
-function callWithTrustedClick(callback) {
-  return waitForDocumentReady().then(() => new Promise(resolve => {
-                                       let button =
-                                           document.createElement('button');
-                                       button.textContent =
-                                           'click to continue test';
-                                       button.style.display = 'block';
-                                       button.style.fontSize = '20px';
-                                       button.style.padding = '10px';
-                                       button.onclick = () => {
-                                         document.body.removeChild(button);
-                                         resolve(callback());
-                                       };
-                                       document.body.appendChild(button);
-                                       test_driver.click(button);
-                                     }));
+async function callWithTrustedClick(callback) {
+  await waitForDocumentReady();
+  return new Promise(resolve => {
+    let button = document.createElement('button');
+    button.textContent = 'click to continue test';
+    button.style.display = 'block';
+    button.style.fontSize = '20px';
+    button.style.padding = '10px';
+    button.onclick = () => {
+      document.body.removeChild(button);
+      resolve(callback());
+    };
+    document.body.appendChild(button);
+    test_driver.click(button);
+  });
 }
 
 /**
@@ -356,7 +350,7 @@ function assert_promise_resolves_after_event(
  * @returns {Promise<void>} Resolves if no events were fired.
  */
 function assert_no_events(object, event_name) {
-  return new Promise((resolve, reject) => {
+  return new Promise((resolve) => {
     let event_listener = (e) => {
       object.removeEventListener(event_name, event_listener);
       assert_unreached('Object should not fire an event.');
diff --git a/tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document-meta.html b/tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document-meta.sub.html
similarity index 79%
rename from tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document-meta.html
rename to tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document-meta.sub.html
index f3750b1e7d8..28129184bda 100644
--- a/tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document-meta.html
+++ b/tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document-meta.sub.html
@@ -9,8 +9,8 @@
       {
         iframe.name = "theiframe";
         iframe.src =
-          "http://www1.{{host}}/content-security-policy/support/frame.html#0";
-        let iframeLoaded = new Promise(resolve => { iframe.onload = resolve; });
+          "http://www1.{{host}}:{{ports[http][0]}}/content-security-policy/frame-src/support/frame.html?0";
+        let iframeLoaded = new Promise(resolve => { iframe.onload = resolve });
         document.body.appendChild(iframe);
         await iframeLoaded;
       }
@@ -26,10 +26,10 @@
       // 3. Blocked same-document navigation using iframe.src.
       {
         let violation = new Promise(resolve => {
-          window.addEventListener('securitypolicyviolation', resolve);
+          window.addEventListener('securitypolicyviolation', () => resolve());
         });
         iframe.src =
-          "http://www1.{{host}}/content-security-policy/support/frame.html#1";
+          "http://www1.{{host}}:{{ports[http][0]}}/content-security-policy/frame-src/support/frame.html?1";
         await violation;
       }
 
@@ -39,7 +39,7 @@
           window.addEventListener('securitypolicyviolation', resolve);
         });
         window.open(
-          "http://www1.{{host}}/content-security-policy/support/frame.html#2",
+          "http://www1.{{host}}:{{ports[http][0]}}/content-security-policy/frame-src/support/frame.html?2",
           "theiframe");
         await violation;
       }
diff --git a/tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document.html b/tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document.sub.html
similarity index 87%
rename from tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document.html
rename to tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document.sub.html
index 398d0223bcb..eeda05bb43b 100644
--- a/tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document.html
+++ b/tests/wpt/web-platform-tests/content-security-policy/frame-src/frame-src-same-document.sub.html
@@ -4,7 +4,7 @@
 <body></body>
 <script>
     let crossOriginUrl =
-      "http://www1.{{host}}/content-security-policy/support/frame.html";
+      "http://www1.{{host}}:{{ports[http][0]}}/content-security-policy/support/frame.html";
 
     async_test(async test => {
       test.done();
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieListItem_attributes.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieListItem_attributes.tentative.https.any.js
index 1738b8709ab..5d46b2d119c 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieListItem_attributes.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieListItem_attributes.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieListItem attributes
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_empty.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_empty.tentative.https.any.js
index 7df0b7002f3..8cfd732f304 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_empty.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_empty.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: ServiceWorker without cookie change subscriptions
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 // META: script=/service-workers/service-worker/resources/test-helpers.sub.js
 
 'use strict';
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_multiple.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_multiple.tentative.https.any.js
index 030297e4095..cf22e46a194 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_multiple.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_multiple.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: ServiceWorker with multiple cookie change subscriptions
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 // META: script=/service-workers/service-worker/resources/test-helpers.sub.js
 
 'use strict';
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_single.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_single.tentative.https.any.js
index 4b489bd5179..fac0f408e06 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_single.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStoreManager_getSubscriptions_single.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: ServiceWorker with one cookie change subscription
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 // META: script=/service-workers/service-worker/resources/test-helpers.sub.js
 
 'use strict';
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_arguments.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_arguments.tentative.https.any.js
index c201065274e..e2fca75850d 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_arguments.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_arguments.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieStore.delete() arguments
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_basic.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_basic.tentative.https.any.js
index 394e6ecc64e..08a1fac5afe 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_basic.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_basic.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieStore.delete() return type
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_insecure.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_insecure.tentative.https.any.js
index e97401a7cce..aec0e28615c 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_insecure.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_delete_insecure.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieStore.delete() with insecure cookies
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_arguments.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_arguments.tentative.https.any.js
index 90dac6466c1..ab88ec30804 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_arguments.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_arguments.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieStore.getAll() arguments
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_multiple.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_multiple.tentative.https.any.js
index 1b094af67b0..10dcacbd688 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_multiple.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_multiple.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieStore.getAll() with multiple cookies
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_set_basic.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_set_basic.tentative.https.any.js
index f1be8208f38..dee78e1867c 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_set_basic.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_getAll_set_basic.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: Interaction between cookieStore.set() and cookieStore.getAll()
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_arguments.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_arguments.tentative.https.any.js
index b0bef77fd89..4cf596bbec2 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_arguments.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_arguments.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieStore.get() arguments
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_delete_basic.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_delete_basic.tentative.https.any.js
index d71afe2044c..6c744533321 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_delete_basic.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_delete_basic.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: Interaction between cookieStore.set() and cookieStore.delete()
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_set_basic.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_set_basic.tentative.https.any.js
index 79d2f4321de..127f758f5f0 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_set_basic.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_set_basic.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: Interaction between cookieStore.set() and cookieStore.get()
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_set_ordering.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_set_ordering.tentative.https.any.js
index 0ec3feff205..6b7e73950cb 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_set_ordering.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_get_set_ordering.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: Cookie ordering
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_set_arguments.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_set_arguments.tentative.https.any.js
index 5668b858be0..528bc9de6c1 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_set_arguments.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_set_arguments.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieStore.set() arguments
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_special_names.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_special_names.tentative.https.any.js
index 14196667fbb..0cf4edc7543 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_special_names.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_special_names.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieStore.set()/get()/delete() for cookies with special names
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookieStore_subscribe_arguments.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/cookieStore_subscribe_arguments.tentative.https.any.js
index d82c71f177f..e3401ca46a4 100644
--- a/tests/wpt/web-platform-tests/cookie-store/cookieStore_subscribe_arguments.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/cookieStore_subscribe_arguments.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookieStore.subscribe() arguments
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 // META: script=/service-workers/service-worker/resources/test-helpers.sub.js
 
 'use strict';
diff --git a/tests/wpt/web-platform-tests/cookie-store/encoding.https.any.js b/tests/wpt/web-platform-tests/cookie-store/encoding.https.any.js
index 41ce747f814..941639bdaec 100644
--- a/tests/wpt/web-platform-tests/cookie-store/encoding.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/encoding.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookie encoding
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 // META: script=resources/cookie-test-helpers.js
 
 'use strict';
diff --git a/tests/wpt/web-platform-tests/cookie-store/idlharness.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/idlharness.tentative.https.any.js
index 0c7a5150237..b9a2aae7848 100644
--- a/tests/wpt/web-platform-tests/cookie-store/idlharness.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/idlharness.tentative.https.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,serviceworker,window
+// META: global=window,serviceworker
 // META: timeout=long
 // META: script=/resources/WebIDLParser.js
 // META: script=/resources/idlharness.js
diff --git a/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_mismatched_subscription.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_mismatched_subscription.tentative.https.any.js
index bfbea7d3de3..b1e412c7997 100644
--- a/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_mismatched_subscription.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_mismatched_subscription.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookiechange event in ServiceWorker with mismatched subscription
-// META: global=!default,serviceworker
+// META: global=serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_multiple_subscriptions.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_multiple_subscriptions.tentative.https.any.js
index 17baa7fcbee..f983f54b44a 100644
--- a/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_multiple_subscriptions.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_multiple_subscriptions.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookiechange event in ServiceWorker with multiple subscriptions
-// META: global=!default,serviceworker
+// META: global=serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_overlapping_subscriptions.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_overlapping_subscriptions.tentative.https.any.js
index b1cbeb9a12f..b4089030e6b 100644
--- a/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_overlapping_subscriptions.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_overlapping_subscriptions.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookiechange event in ServiceWorker with overlapping subscriptions
-// META: global=!default,serviceworker
+// META: global=serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_single_subscription.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_single_subscription.tentative.https.any.js
index 4cfc47b39fb..b38d91a3c65 100644
--- a/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_single_subscription.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/serviceworker_cookiechange_eventhandler_single_subscription.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: cookiechange event in ServiceWorker with single subscription
-// META: global=!default,serviceworker
+// META: global=serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/cookie-store/serviceworker_oncookiechange_eventhandler_single_subscription.tentative.https.any.js b/tests/wpt/web-platform-tests/cookie-store/serviceworker_oncookiechange_eventhandler_single_subscription.tentative.https.any.js
index d3fe3281aca..1921583e5c5 100644
--- a/tests/wpt/web-platform-tests/cookie-store/serviceworker_oncookiechange_eventhandler_single_subscription.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/cookie-store/serviceworker_oncookiechange_eventhandler_single_subscription.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Cookie Store API: oncookiechange event in ServiceWorker with single subscription
-// META: global=!default,serviceworker
+// META: global=serviceworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/css/css-animations/Document-getAnimations.tentative.html b/tests/wpt/web-platform-tests/css/css-animations/Document-getAnimations.tentative.html
index 4416735f50b..758f6809495 100644
--- a/tests/wpt/web-platform-tests/css/css-animations/Document-getAnimations.tentative.html
+++ b/tests/wpt/web-platform-tests/css/css-animations/Document-getAnimations.tentative.html
@@ -18,6 +18,20 @@
 @keyframes animRight {
   to { right: 100px }
 }
+
+@keyframes anim1 {
+  to { left: 100px }
+}
+@keyframes anim2 {
+  to { top: 100px }
+}
+@keyframes anim3 {
+  to { bottom: 100px }
+}
+@keyframes anim4 {
+  to { right: 100px }
+}
+
 </style>
 <div id="log"></div>
 <script>
@@ -285,6 +299,84 @@ test(t => {
                 'returned');
 }, 'CSS Animations canceled and restarted via the API are returned');
 
+test(t => {
+  addStyle(t, {
+      '#parent::after': "content: ''; animation: anim1 100s ; ",
+      '#parent::before': "content: ''; animation: anim2 100s;",
+      '#child::after': "content: ''; animation: anim3 100s;",
+      '#child::before': "content: ''; animation: anim4 100s;",
+    });
+  const parent = addDiv(t, { id: 'parent' });
+  const child = addDiv(t, { id: 'child'});
+  parent.appendChild(child);
+  var animations = document.getAnimations();
+  var expectedAnimations = [
+      [parent, '::before', 'anim2'],
+      [parent, '::after', 'anim1'],
+      [child, '::before', 'anim4'],
+      [child, '::after', 'anim3'],
+    ];
+  pseudoAnimCompare(animations, expectedAnimations)
+
+  // Swap animation1 and aimation3's effect
+  var anim1 = animations[0];
+  var anim3 = animations[2];
+  const temp = anim1.effect;
+  anim1.effect = anim3.effect;
+  anim3.effect = temp;
+
+  animations = document.getAnimations();
+  expectedAnimations = [
+      [child, '::before', 'anim2'],
+      [parent, '::after', 'anim1'],
+      [parent, '::before', 'anim4'],
+      [child, '::after', 'anim3'],
+    ];
+  pseudoAnimCompare(animations, expectedAnimations)
+}, 'pseudo element with replaced target does not affect animation ordering');
+
+function pseudoAnimCompare(animations, expectedAnimations) {
+  assert_equals(
+      animations.length,
+      expectedAnimations.length,
+      'CSS animations on both pseudo-elements and elements are returned'
+    );
+  for (const [index, expected] of expectedAnimations.entries()) {
+      const [element, pseudo, name] = expected;
+      const actual = animations[index];
+      if (pseudo) {
+        assert_equals(
+          actual.effect.target,
+          element,
+          `Animation #${index + 1} has the expected target`
+        );
+        assert_equals(
+          actual.effect.pseudoElement,
+          pseudo,
+          `Animation #${index + 1} has the expected pseudo type`
+        );
+        if (name) {
+          assert_equals(
+            actual.animationName,
+            name,
+            `Animation #${index + 1} has the expected name`
+          );
+        }
+      } else {
+        assert_equals(
+          actual.effect.target,
+          element,
+          `Animation #${index + 1} has the expected target`
+        );
+        assert_equals(
+          actual.effect.pseudoElement,
+          null,
+          `Animation #${index + 1} has a null pseudo type`
+        );
+      }
+    }
+}
+
 function pseudoTest(description, testMarkerPseudos) {
   test(t => {
     // Create two divs with the following arrangement:
@@ -327,40 +419,7 @@ function pseudoTest(description, testMarkerPseudos) {
     }
 
     const animations = document.getAnimations();
-    assert_equals(
-      animations.length,
-      expectedAnimations.length,
-      'CSS animations on both pseudo-elements and elements are returned'
-    );
-
-    for (const [index, expected] of expectedAnimations.entries()) {
-      const [element, pseudo] = expected;
-      const actual = animations[index];
-
-      if (pseudo) {
-        assert_equals(
-          actual.effect.target,
-          element,
-          `Animation #${index + 1} has expected target`
-        );
-        assert_equals(
-          actual.effect.pseudoElement,
-          pseudo,
-          `Animation #${index + 1} has expected pseudo type`
-        );
-      } else {
-        assert_equals(
-          actual.effect.target,
-          element,
-          `Animation #${index + 1} has expected target`
-        );
-        assert_equals(
-          actual.effect.pseudoElement,
-          null,
-          `Animation #${index + 1} has null pseudo type`
-        );
-      }
-    }
+    pseudoAnimCompare(animations, expectedAnimations)
   }, description);
 }
 
@@ -368,5 +427,4 @@ pseudoTest('CSS Animations targetting (pseudo-)elements should have correct '
      + 'order after sorting', false);
 pseudoTest('CSS Animations targetting (pseudo-)elements should have correct '
      + 'order after sorting (::marker)', true);
-
 </script>
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-001-ref.html b/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-001-ref.html
new file mode 100644
index 00000000000..ee25fd250ed
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-001-ref.html
@@ -0,0 +1,14 @@
+<!doctype HTML>
+<style>
+  div {
+    background: linear-gradient(rgba(0,255,0,0.5), rgba(0,0,255,0.5)), linear-gradient(rgba(0,0,0,1), rgba(0,0,0,1));
+    background-size: 100px 100px, 100px 100px;
+    background-position: 50px 50px, 0 0;
+    position: absolute;
+    top: 0;
+    left: 0;
+    right: 0;
+    bottom: 0;
+  }
+</style>
+<div></div>
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-001.html b/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-001.html
new file mode 100644
index 00000000000..88bc2845e8b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-001.html
@@ -0,0 +1,15 @@
+<!doctype HTML>
+<title>Background-attachment: scroll should be positioned relative to the root element and should extend to cover the entire canvas in the presence of fixed backgrounds</title>
+<link rel="author" title="Philip Rogers" href="mailto:pdr@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-backgrounds-3/#root-background">
+<link rel="help" href="https://drafts.csswg.org/css-backgrounds-3/#the-background-attachment">
+<link rel="match" href="background-attachment-margin-root-001-ref.html">
+<style>
+  html {
+    background: linear-gradient(rgba(0,255,0,0.5), rgba(0,0,255,0.5)), linear-gradient(rgba(0,0,0,1), rgba(0,0,0,1));
+    background-attachment: scroll, fixed;
+    background-size: 100px 100px, 100px 100px;
+    height: 300px;
+    margin: 50px;
+  }
+</style>
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-002-ref.html b/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-002-ref.html
new file mode 100644
index 00000000000..9fb084071c5
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-002-ref.html
@@ -0,0 +1,14 @@
+<!doctype HTML>
+<style>
+  div {
+    background: linear-gradient(rgba(0,255,0,0.5), rgba(0,0,255,0.5)), linear-gradient(rgba(0,0,0,1), rgba(0,0,0,1));
+    background-size: 100px 100px, 100px 100px;
+    background-position: 0 0, 0 0;
+    position: absolute;
+    top: 0;
+    left: 0;
+    right: 0;
+    bottom: 0;
+  }
+</style>
+<div></div>
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-002.html b/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-002.html
new file mode 100644
index 00000000000..4ee882f9da9
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/background-attachment-margin-root-002.html
@@ -0,0 +1,15 @@
+<!doctype HTML>
+<title>Background-attachment: fixed should be positioned relative to the view and should extend to cover the entire canvas in the presence of scroll backgrounds</title>
+<link rel="author" title="Philip Rogers" href="mailto:pdr@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-backgrounds-3/#root-background">
+<link rel="help" href="https://drafts.csswg.org/css-backgrounds-3/#the-background-attachment">
+<link rel="match" href="background-attachment-margin-root-002-ref.html">
+<style>
+  html {
+    background: linear-gradient(rgba(0,255,0,0.5), rgba(0,0,255,0.5)), linear-gradient(rgba(0,0,0,1), rgba(0,0,0,1));
+    background-attachment: fixed, scroll;
+    background-size: 100px 100px, 100px 100px;
+    height: 300px;
+    margin: 50px;
+  }
+</style>
diff --git a/tests/wpt/web-platform-tests/css/css-break/remove-inline-child.html b/tests/wpt/web-platform-tests/css/css-break/remove-inline-child.html
new file mode 100644
index 00000000000..64f4d0b1ac2
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-break/remove-inline-child.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://bugs.chromium.org/p/chromium/issues/detail?id=1075517">
+<div style="columns:2; column-fill:auto; line-height:20px; height:50px;">
+  <div>
+    <span id="removeme">
+      line1<br>
+      line2<br>
+      line3<br>
+      line4<br>
+    </span>
+  </div>
+</div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+  test(()=> {
+      document.body.offsetTop;
+      removeme.style.display = "none";
+  }, "no crash");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-flexbox/negative-item-margins-crash.html b/tests/wpt/web-platform-tests/css/css-flexbox/negative-item-margins-crash.html
new file mode 100644
index 00000000000..d5f9365b5ec
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-flexbox/negative-item-margins-crash.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<title>min-width: auto, negative margins</title>
+<link rel="author" title="David Grogan" href="mailto:dgrogan@chromium.org" />
+<link rel="help" href="https://drafts.csswg.org/css-flexbox/#min-size-auto" />
+<link rel="issue" href="https://crbug.com/1075908" />
+
+<p>Test passes if it doesn't crash.</p>
+
+<div style="display: flex">
+  <div style="flex-basis: 0; margin: -10px;">
+    <div style="width: 100px"></div>
+  </div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-001-ref.html
new file mode 100644
index 00000000000..fff6cf21381
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-001-ref.html
@@ -0,0 +1,125 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `align-content` in masonry axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: 1em auto;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  height: 100px;
+  align-items: start;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { padding-top:30px; grid-row:span 2; }
+</style>
+</head>
+<body>
+
+<grid style="align-content:start">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:stretch">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-001.html
new file mode 100644
index 00000000000..dfefd998c65
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-001.html
@@ -0,0 +1,125 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `align-content` in masonry axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-align-content-001-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  height: 100px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+</style>
+</head>
+<body>
+
+<grid style="align-content:start">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:stretch">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-between">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-around">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-evenly">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-002-ref.html
new file mode 100644
index 00000000000..67318b323a2
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-002-ref.html
@@ -0,0 +1,126 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `align-content` in masonry axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: 1em auto;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  width: 100px;
+  align-items: start;
+  writing-mode: vertical-lr;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { padding-right:30px; grid-row:span 2; }
+</style>
+</head>
+<body>
+
+<grid style="align-content:start">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:stretch">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-002.html
new file mode 100644
index 00000000000..75b82654fea
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-002.html
@@ -0,0 +1,126 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `align-content` in masonry axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-align-content-002-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  width: 100px;
+  writing-mode: vertical-lr;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+</style>
+</head>
+<body>
+
+<grid style="align-content:start">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item>1</item>
+  <item style="padding-right:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item>1</item>
+  <item style="padding-right:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item>1</item>
+  <item style="padding-right:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:stretch">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-between">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-around">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-evenly">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-003-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-003-ref.html
new file mode 100644
index 00000000000..9780d5f5dcf
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-003-ref.html
@@ -0,0 +1,127 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `align-content` in grid axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: 1ch auto;
+  grid-template-rows: repeat(4,auto);
+  background: content-box silver;
+  border: 1px solid;
+  padding: 0 3px 2px 0;
+  width: 100px;
+  height: 120px;
+  align-content: center;
+  justify-items: start;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { grid-row: span 2; padding: 3px 11px 1px 13px; }
+</style>
+</head>
+<body>
+
+<grid style="align-content:start">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:stretch">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:space-between">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:space-around">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:space-evenly">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-003.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-003.html
new file mode 100644
index 00000000000..ae58e79cb2b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-003.html
@@ -0,0 +1,129 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `align-content` in grid axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-align-content-003-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: masonry;
+  grid-template-rows: repeat(4,auto);
+  background: content-box silver;
+  border: 1px solid;
+  padding: 0 3px 2px 0;
+  width: 100px;
+  height: 120px;
+  align-content: center;
+  justify-items: start;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { padding: 3px 11px 1px 13px; }
+</style>
+</head>
+<body>
+
+<grid style="align-content:start">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:stretch">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-between">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-around">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-evenly">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-004-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-004-ref.html
new file mode 100644
index 00000000000..de11c836b8d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-004-ref.html
@@ -0,0 +1,126 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `align-content` in grid axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: 1ch auto;
+  grid-template-rows: repeat(4,20px);
+  background: content-box silver;
+  border: 1px solid;
+  padding: 2px;
+  width: 100px;
+  justify-items: start;
+  writing-mode: vertical-rl;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { grid-column: span 2; padding-top: 30px; }
+</style>
+</head>
+<body>
+
+<grid style="align-content:start">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:stretch">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:space-between">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:space-around">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="align-content:space-evenly">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-004.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-004.html
new file mode 100644
index 00000000000..3f07aa1fe75
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-content-004.html
@@ -0,0 +1,127 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `align-content` in grid axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-align-content-004-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: masonry;
+  grid-template-rows: repeat(4,20px);
+  background: content-box silver;
+  border: 1px solid;
+  padding: 2px;
+  width: 100px;
+  writing-mode: vertical-rl;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { padding-top: 30px; }
+</style>
+</head>
+<body>
+
+<grid style="align-content:start">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:start">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:end">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:center">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:stretch">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-between">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-around">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="align-content:space-evenly">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-001-ref.html
new file mode 100644
index 00000000000..3b22489fdb9
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-001-ref.html
@@ -0,0 +1,120 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `align-tracks` alignment</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; direction:ltr; }
+.swr { writing-mode: sideways-lr; direction:rtl; }
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  background: content-box silver;
+  color: #444;
+  padding: 1px 2px;
+  block-size: 30px;
+  vertical-align: top;
+}
+grid.vll, grid.vrr, grid.vlr, grid.vrl, grid.swl, grid.swr {
+  inline-size: 22px;
+}
+
+grid > div {
+  display: inline-flex;
+  inline-size: min-content;
+}
+
+grid2 {
+  display: inline-grid;
+  row-gap: 1px;
+  grid-template-columns: 8px;
+  vertical-align: top;
+  block-size: 21px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  writing-mode: horizontal-tb;
+  direction: ltr;
+}
+grid2:nth-child(1) {
+  grid-template-rows: 8px 8px;
+  margin-inline-end: 2px;
+}
+grid2:nth-child(2) {
+  grid-template-rows: 12px 8px;
+}
+
+.vll grid2:nth-child(1) { block-size:17px; }
+.vrr grid2:nth-child(1) { block-size:17px; }
+.vlr grid2:nth-child(1) { block-size:17px; }
+.vrl grid2:nth-child(1) { block-size:17px; }
+.swl grid2:nth-child(1) { block-size:17px; }
+.swr grid2:nth-child(1) { block-size:17px; }
+
+.vll grid2:nth-child(2) { grid-template-rows:8px 8px; }
+.vrr grid2:nth-child(2) { grid-template-rows:8px 8px; }
+.vlr grid2:nth-child(2) { grid-template-rows:8px 8px; }
+.vrl grid2:nth-child(2) { grid-template-rows:8px 8px; }
+.swl grid2:nth-child(2) { grid-template-rows:8px 8px; }
+.swr grid2:nth-child(2) { grid-template-rows:8px 8px; }
+
+grid2:nth-child(1) > item:nth-child(1) { background: blue; inline-size:8px; block-size:8px; z-index:1; }
+grid2:nth-child(2) > item:nth-child(1) { background: magenta; inline-size:8px; block-size:12px; z-index:1; }
+grid2:nth-child(1) > item:nth-child(2) { background: lime; inline-size:12px; block-size:8px; z-index:2; }
+grid2:nth-child(2) > item:nth-child(2) { background: purple; inline-size:8px; block-size:8px; z-index:2; }
+</style>
+</head>
+<body>
+<div style="display:none">
+<grid>
+ <div>
+  <grid2>
+    <item></item>
+    <item></item>
+  </grid2><grid2>
+    <item></item>
+    <item></item>
+  </grid2>
+ </div>
+</grid>
+</div>
+
+<script>
+let wms = [ "hl", "hr", "vll", "vrr", "vlr", "vrl", "swl", "swr", ];
+let ats = [ "start", "self-start", "center", "end", "self-end", "stretch", "space-between", "space-around", "space-evenly", ];
+let acs = [ "start", "center", "end", ];
+let grid = document.getElementsByTagName('grid')[0];
+for (const ac of acs) {
+  for (const at of ats) {
+    for (const wm of wms) {
+      let e = grid.cloneNode(true);
+      e.className = wm;
+      e.children[0].children[1].style.className = wm;
+      e.children[0].children[0].style.alignContent = at;
+      e.children[0].children[1].style.alignContent = at;
+      e.style.alignContent = ac;
+      document.body.appendChild(e);
+    }
+  }
+}
+</script>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-001.html
new file mode 100644
index 00000000000..4ff3e610875
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-001.html
@@ -0,0 +1,80 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `align-tracks` alignment</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-align-tracks-001-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; direction:ltr; }
+.swr { writing-mode: sideways-lr; direction:rtl; }
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(2,auto);
+  grid-template-rows: masonry;
+  background: content-box silver;
+  color: #444;
+  padding: 1px 2px;
+  block-size: 30px;
+  vertical-align: top;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  writing-mode: horizontal-tb;
+  direction: ltr;
+}
+
+item:nth-child(1) { background: blue; inline-size:8px; block-size:8px; }
+item:nth-child(2) { background: magenta; inline-size:8px; block-size:12px; }
+item:nth-child(3) { background: lime; inline-size:12px; block-size:8px; }
+item:nth-child(4) { background: purple; inline-size:8px; block-size:8px; }
+</style>
+</head>
+<body>
+<div style="display:none">
+<grid>
+  <item></item>
+  <item></item>
+  <item></item>
+  <item></item>
+</grid>
+</div>
+
+<script>
+let wms = [ "hl", "hr", "vll", "vrr", "vlr", "vrl", "swl", "swr", ];
+let ats = [ "start", "self-start", "center", "end", "self-end", "stretch", "space-between", "space-around", "space-evenly", ];
+let acs = [ "start", "center", "end", ];
+let grid = document.getElementsByTagName('grid')[0];
+for (const ac of acs) {
+  for (const at of ats) {
+    for (const wm of wms) {
+      let e = grid.cloneNode(true);
+      e.className = wm;
+      e.style.alignTracks = at;
+      e.style.alignContent = ac;
+      document.body.appendChild(e);
+    }
+  }
+}
+</script>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-multi-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-multi-001-ref.html
new file mode 100644
index 00000000000..11ff5081ec1
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-multi-001-ref.html
@@ -0,0 +1,116 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with multiple `align-tracks` values</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+<style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-rows: auto;
+  grid-template-columns: repeat(8,50px); /*intentionally one more than align-tracks values*/
+  gap: 3px 5px;
+  padding: 10px 3px 1px 7px;
+  border: solid;
+  border-width: 1px 7px 3px 5px;
+  background: lightgrey content-box;
+  height: 500px;
+  vertical-align: top;
+}
+.fallback { grid-template-columns:3px; padding:0; border:0; }
+item {
+  background: grey;
+  height: 2em;
+  position: relative;
+  border: 1px solid;
+}
+.purple { background:purple; height:auto; border-top:3px solid; }
+z { display: block; background: yellow; height: 0; width:80%; }
+a {
+ position: absolute;
+ inset: 0;
+ top: auto;
+ border: 2px solid lime;
+}
+masonry-track {
+  display: grid;
+  gap: 3px 5px;
+}
+masonry-track:nth-child(1) { align-content:start }
+masonry-track:nth-child(2) { align-content:end }
+masonry-track:nth-child(3) { align-content:center }
+masonry-track:nth-child(4) { align-content:stretch; grid-template-rows: auto auto repeat(3,max-content) }
+masonry-track:nth-child(5) { align-content:space-between }
+masonry-track:nth-child(6) { align-content:space-around }
+masonry-track:nth-child(7) { align-content:space-evenly }
+masonry-track:nth-child(8) { align-content:space-evenly }
+</style>
+</head>
+<body>
+<grid>
+ <masonry-track>
+  <item style="width:25px">1</item>
+  <item>11</item>
+  <item class="purple">20</item>
+  <item class="purple">24</item>
+  <item>29</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple" style="height:50px">2</item>
+  <item class="purple" style="writing-mode:vertical-rl">16 vertical-rl</item>
+ </masonry-track>
+ <masonry-track>
+  <item style="margin-left:5px">3</item>
+  <item class="purple">12<z></z></item>
+  <item>17</item>
+  <item>25</item>
+  <item>33</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple" style="margin-top:5px">4</item>
+  <item class="purple">10</item>
+  <item>15</item>
+  <item>23</item>
+  <item>31</item>
+ </masonry-track>
+ <masonry-track>
+  <item>5</item>
+  <item>13</item>
+  <item>21</item>
+  <item class="purple">28</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">6<a></a></item>
+  <item>9<a></a></item>
+  <item class="purple">18</item>
+  <item class="purple">22</item>
+  <item>27</item>
+ </masonry-track>
+ <masonry-track>
+  <item>7</item>
+  <item class="purple">14<z></z><a></a></item>
+  <item>19</item>
+  <item class="purple">26</item>
+  <item class="purple">30</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple" style="writing-mode:vertical-lr">8 vertical-lr</item>
+  <item class="purple">32</item>
+ </masonry-track>
+</grid>
+<grid class="fallback" style="align-content:start">
+  <item></item>
+</grid>
+<grid class="fallback" style="align-content:center">
+  <item></item>
+</grid>
+<grid class="fallback" style="align-content:center">
+  <item></item>
+</grid>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-multi-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-multi-001.html
new file mode 100644
index 00000000000..2dcdfe4b4be
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-multi-001.html
@@ -0,0 +1,91 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with multiple `align-tracks` values</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-align-tracks-multi-001-ref.html">
+<style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-rows: masonry;
+  grid-template-columns: repeat(8,50px); /*intentionally one more than align-tracks values*/
+  gap: 3px 5px;
+  padding: 10px 3px 1px 7px;
+  border: solid;
+  border-width: 1px 7px 3px 5px;
+  background: lightgrey content-box;
+  align-tracks: start,end,center,stretch,space-between,space-around,space-evenly;
+  height: 500px;
+  vertical-align: top;
+}
+.fallback { grid-template-columns:3px; padding:0; border:0; }
+item {
+  background: grey;
+  height: 2em;
+  position: relative;
+  border: 1px solid;
+}
+item:nth-child(2n) { background:purple; height:auto; border-top:3px solid; }
+z { display: block; background: yellow; height: 20%; width:80%; }
+a {
+ position: absolute;
+ inset: 0;
+ top: auto;
+ border: 2px solid lime;
+}
+</style>
+</head>
+<body>
+<grid>
+  <item style="width:50%">1</item>
+  <item style="height:10%">2</item>
+  <item style="margin-left:10%">3</item>
+  <item style="margin-top:10%">4</item>
+  <item>5</item>
+  <item>6<a></a></item>
+  <item>7</item>
+  <item style="writing-mode:vertical-lr">8 vertical-lr</item>
+  <item>9<a></a></item>
+  <item>10</item>
+  <item>11</item>
+  <item>12<z></z></item>
+  <item>13</item>
+  <item><z></z>14<a></a></item>
+  <item>15</item>
+  <item style="writing-mode:vertical-rl">16 vertical-rl</item>
+  <item>17</item>
+  <item>18</item>
+  <item>19</item>
+  <item>20</item>
+  <item>21</item>
+  <item>22</item>
+  <item>23</item>
+  <item>24</item>
+  <item>25</item>
+  <item>26</item>
+  <item>27</item>
+  <item>28</item>
+  <item>29</item>
+  <item>30</item>
+  <item>31</item>
+  <item>32</item>
+  <item>33</item>
+</grid>
+<grid class="fallback" style="align-tracks:space-between">
+  <item></item>
+</grid>
+<grid class="fallback" style="align-tracks:space-around">
+  <item></item>
+</grid>
+<grid class="fallback" style="align-tracks:space-evenly">
+  <item></item>
+</grid>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-001-ref.html
new file mode 100644
index 00000000000..0712f14bb31
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-001-ref.html
@@ -0,0 +1,87 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `align-tracks:stretch`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+<style>
+html,body {
+  color:black; background-color:white; font:16px/1 Ahem; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-rows: 500px;
+  grid-template-columns: 150px 100px 50px;
+  gap: 3px 5px;
+  padding: 10px;
+  border: 3px solid;
+  background: lightgrey content-box;
+  height: 500px;
+}
+masonry-track {
+  display: grid;
+  gap: 3px 5px;
+  align-content: stretch;
+  height: 500px;
+}
+masonry-track:nth-child(1) {
+  grid-template-columns: 150px;
+  grid-template-rows: min-content min-content min-content auto min-content min-content min-content;
+}
+masonry-track:nth-child(2) {
+  grid-template-columns: 100px;
+  grid-template-rows: auto 50px auto auto 30px;
+}
+masonry-track:nth-child(3) {
+  grid-template-columns: 50px;
+  grid-template-rows: 30px 30px 30px auto 30px 30px auto auto;
+}
+item {
+  background: grey;
+  height: 30px;
+  position: relative;
+}
+.purple { background:purple; height:auto; }
+z { display: block; background: yellow; height: 20%; width:80%; }
+a {
+ position: absolute;
+ inset: 0;
+ top: auto;
+ border: 2px solid lime;
+}
+</style>
+</head>
+<body>
+<grid>
+ <masonry-track>
+  <item style="border:10px solid; margin: 10px 0 5px 3px;">1</item>
+  <item>9<a></a></item>
+  <item>11</item>
+  <item class="purple">12<br><br><z></z></item>
+  <item class="purple" style="height:116px; border:2px solid; margin:1px">14<z></z><a></a></item>
+  <item style="align-self:start" class="purple">16</item>
+  <item>17</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item style="height:40px; margin-top:10px" class="purple">4</item>
+  <item class="purple">6<a></a></item>
+  <item style="writing-mode:vertical-lr" class="purple">8 vertical</item>
+  <item>19</item>
+ </masonry-track>
+ <masonry-track>
+  <item>3</item>
+  <item>5</item>
+  <item>7</item>
+  <item class="purple">10 A<br>B</item>
+  <item>13</item>
+  <item>15</item>
+  <item style="margin:auto 0" class="purple">18</item>
+  <item style="margin-top: auto" class="purple">20</item>
+ </masonry-track>
+</grid>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-001.html
new file mode 100644
index 00000000000..d2fede7a8ed
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-001.html
@@ -0,0 +1,67 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `align-tracks:stretch`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-align-tracks-stretch-001-ref.html">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+<style>
+html,body {
+  color:black; background-color:white; font:16px/1 Ahem; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-rows: masonry;
+  grid-template-columns: 150px 100px 50px;
+  gap: 3px 5px;
+  padding: 10px;
+  border: 3px solid;
+  background: lightgrey content-box;
+  align-tracks: stretch;
+  height: 500px;
+}
+item {
+  background: grey;
+  height: 30px;
+  position: relative;
+}
+item:nth-child(2n) { background:purple; height:auto; }
+item:nth-child(1) { border:10px solid; margin: 10px 0 5px 3px; }
+z { display: block; background: yellow; height: 20%; width:80%; }
+a {
+ position: absolute;
+ inset: 0;
+ top: auto;
+ border: 2px solid lime;
+}
+</style>
+</head>
+<body>
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="max-height:40px; margin-top:10px">4</item>
+  <item>5</item>
+  <item>6<a></a></item>
+  <item>7</item>
+  <item style="writing-mode:vertical-lr">8 vertical</item>
+  <item>9<a></a></item>
+  <item>10 A<br>B</item>
+  <item>11</item>
+  <item>12<br><br><z></z></item>
+  <item>13</item>
+  <item style="max-height:120px; border:2px solid; box-sizing:border-box; margin:1px">14<z></z><a></a></item>
+  <item>15</item>
+  <item style="align-self:end">16</item>
+  <item>17</item>
+  <item style="margin:auto 0">18</item>
+  <item>19</item>
+  <item style="margin-top: auto">20</item>
+</grid>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-002-ref.html
new file mode 100644
index 00000000000..01f24ea986f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-002-ref.html
@@ -0,0 +1,68 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `align-tracks:stretch`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+<style>
+html,body {
+  color:black; background-color:white; font:6px/1 monospace; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-rows: auto auto;
+  grid-template-columns: 30px;
+  gap: 1px 2px;
+  padding: 2px 3px 1px 1px;
+  border-style: solid;
+  border-width: 1px 7px 3px 5px;
+  border-inline-start-color: magenta;
+  border-block-start-color: blue;
+  background: lightgrey content-box;
+  block-size: 25px;
+  vertical-align: top;
+}
+item {
+  border-inline-start: 1px solid magenta;
+  border-block-start: 2px solid blue;
+}
+item:nth-child(2n+1) { background: grey; }
+item:nth-child(2n) { background: cyan; }
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; direction:ltr; }
+.swr { writing-mode: sideways-lr; direction:rtl; }
+</style>
+</head>
+<body>
+<div style="display:none">
+<grid>
+  <item>1</item>
+  <item>2a<br>2b</item>
+</grid>
+</div>
+<script>
+let wms = [ "hl", "hr", "vll", "vrr", "vlr", "vrl", "swl", "swr", ];
+let grid = document.getElementsByTagName('grid')[0];
+for (const reorder of [false, true]) {
+  for (const cb_wm of wms) {
+    for (const child_wm of wms) {
+      let e = grid.cloneNode(true);
+      e.className = cb_wm;
+      e.children[1].className = child_wm;
+      if (reorder) {
+        e.children[0].style.order = '1';
+      }
+      document.body.appendChild(e);
+    }
+  }
+}
+</script>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-002.html
new file mode 100644
index 00000000000..1631ac3c07d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-align-tracks-stretch-002.html
@@ -0,0 +1,71 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `align-tracks:stretch`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-align-tracks-stretch-002-ref.html">
+<style>
+html,body {
+  color:black; background-color:white; font:6px/1 monospace; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-rows: masonry;
+  grid-template-columns: 30px;
+  gap: 1px 2px;
+  padding: 2px 3px 1px 1px;
+  border-style: solid;
+  border-width: 1px 7px 3px 5px;
+  border-inline-start-color: magenta;
+  border-block-start-color: blue;
+  background: lightgrey content-box;
+  align-tracks: stretch;
+  block-size: 25px;
+  vertical-align: top;
+}
+item {
+  border-inline-start: 1px solid magenta;
+  border-block-start: 2px solid blue;
+}
+item:nth-child(2n+1) { background: grey; }
+item:nth-child(2n) { background: cyan; }
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; direction:ltr; }
+.swr { writing-mode: sideways-lr; direction:rtl; }
+</style>
+</head>
+<body>
+<div style="display:none">
+<grid>
+  <item>1</item>
+  <item>2a<br>2b</item>
+</grid>
+</div>
+<script>
+let wms = [ "hl", "hr", "vll", "vrr", "vlr", "vrl", "swl", "swr", ];
+let grid = document.getElementsByTagName('grid')[0];
+for (const reorder of [false, true]) {
+  for (const cb_wm of wms) {
+    for (const child_wm of wms) {
+      let e = grid.cloneNode(true);
+      e.className = cb_wm;
+      e.children[1].className = child_wm;
+      if (reorder) {
+        e.children[0].style.order = '1';
+      }
+      document.body.appendChild(e);
+    }
+  }
+}
+</script>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-001-ref.html
new file mode 100644
index 00000000000..de3fe6f402d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-001-ref.html
@@ -0,0 +1,333 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout fragmentation</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+.columns {
+  width: 330px;
+  columns: 6;
+  column-fill: auto;
+  column-gap: 1px;
+  background-color: rgba(80,80,80,.2);
+  margin-bottom: 10px;
+}
+.columns:nth-child(2n) {
+  background-color: rgba(10,100,10,.5);
+}
+.grid {
+  display: flow-root;
+  border: 1px solid;
+  gap: 2px;
+}
+.first { border-bottom-width:0; height:calc(100% - 1px); }
+.middle { border-top-width:0; border-bottom-width:0; height:100%; }
+.last { border-top-width:0; }
+x {
+  background: cyan;
+  height: 5px;
+}
+y {
+  background: blue;
+  height: 10px;
+}
+z {
+  background: pink;
+  height: 12px;
+}
+masonry-track {
+  float: left;
+  height: 100%;
+  gap: 2px;
+}
+x,y,z,masonry-track { display: block; }
+masonry-track > * { margin-bottom:2px; }
+masonry-track.last > :last-child { margin-bottom:0; }
+masonry-track:nth-child(1) { width: 10px; }
+masonry-track:nth-child(2) { width: 15px; margin-left:2px; }
+masonry-track:nth-child(3) { width: 20px; margin-left:2px; }
+</style></head>
+<body>
+<wrapper>
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y></y><y></y><y></y><x></x><x></x><x></x><x></x></masonry-track>
+    <masonry-track><x></x><z></z><x></x><x></x><x></x><z></z><z></z></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z><x></x><y></y><x></x><x></x><y style="height:9px"></y></masonry-track>
+  </div>
+  <div class="grid last" style="height:1px">
+    <masonry-track></masonry-track>
+    <masonry-track></masonry-track>
+    <masonry-track><y style="height:1px"></y></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y></y><y></y><y></y><x></x><x></x><x></x></masonry-track>
+    <masonry-track><x></x><z></z><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z><x></x><y></y><x></x><x></x></masonry-track>
+  </div>
+  <div class="grid last" style="height:12px">
+    <masonry-track><z></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><y></y></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y></y><y></y><y></y><x></x><x></x></masonry-track>
+    <masonry-track><x></x><z></z><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z><x></x><y></y></masonry-track>
+  </div>
+  <div class="grid last" style="height:24px">
+    <masonry-track><x></x><x></x><y></y></masonry-track>
+    <masonry-track><z></z></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y></y><y></y><y></y></masonry-track>
+    <masonry-track><x></x><z></z><x></x><x></x><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z><x></x><y style="height:5px;"></y></masonry-track>
+  </div>
+  <div class="grid last" style="height:31px">
+    <masonry-track><z></z><z></z></masonry-track>
+    <masonry-track><x></x><x></x><x></x><x></x></masonry-track>
+    <masonry-track><y style="height:5px"></y><x></x><x></x><y></y></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y></y><y></y><y style="height:6px;"></y></masonry-track>
+    <masonry-track><x></x><z></z><x></x><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:4px;"></y><z></z><z></z></masonry-track>
+    <masonry-track><x></x><y></y><x></x><x></x><y style="height:5px;"></y></masonry-track>
+    <masonry-track><x></x><x></x><x></x><x></x><x></x></masonry-track>
+  </div>
+  <div class="grid last" style="height:5px">
+    <masonry-track></masonry-track>
+    <masonry-track><y style="height:5px;"></y></masonry-track>
+    <masonry-track></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y></y><y style="height:8px;"></y></masonry-track>
+    <masonry-track><x></x><z></z><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:2px;"></y><y></y><y></y></masonry-track>
+    <masonry-track><z></z><x></x><x></x></masonry-track>
+    <masonry-track><x></x><x></x><z></z></masonry-track>
+  </div>
+  <div class="grid last" style="height:24px">
+    <masonry-track><x></x><x></x><x></x></masonry-track>
+    <masonry-track><x></x><x></x><y></y></masonry-track>
+    <masonry-track><z></z></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y></y></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z></z></masonry-track>
+    <masonry-track><x></x><x></x><y style="height:4px;"></y></masonry-track>
+    <masonry-track><y></y></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z></z></masonry-track>
+    <masonry-track><y style="height:6px;"></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><y style="height:4px;"></y></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z></z></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+    <masonry-track><y style="height:6px;"></y><x></x></masonry-track>
+  </div>
+  <div class="grid last">
+    <masonry-track><z></z></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+    <masonry-track><x></x><y></y></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y style="height:4px;"></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:6px;"></y><y style="height:4px;"></y></masonry-track>
+    <masonry-track><z style="height:12px;"></z></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:6px;"></y><y style="height:4px;"></y></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+    <masonry-track><z style="height:12px;"></z></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:6px;"></y></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x><y style="height:5px;"></y></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z style="height:12px;"></z></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+    <masonry-track><y style="height:5px;"></y><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z style="height:12px;"></z></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+    <masonry-track><x></x><y style="height:5px;"></y></masonry-track>
+  </div>
+  <div class="grid last" style="height:5px;">
+    <masonry-track></masonry-track>
+    <masonry-track></masonry-track>
+    <masonry-track><y style="height:5px;"></y></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y style="height:3px;"></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:7px;"></y><y style="height:3px;"></y></masonry-track>
+    <masonry-track><z style="height:11px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:8px;"></y></masonry-track>
+    <masonry-track><z style="height:1px;"></z><x></x><y style="height:1px;"></y></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z style="height:11px;"></z></masonry-track>
+    <masonry-track><y style="height:9px;"></y></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z style="height:1px;"></z></masonry-track>
+    <masonry-track><x></x><y style="height:4px;"></y></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z style="height:11px;"></z></masonry-track>
+    <masonry-track><y style="height:6px;"></y></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z style="height:1px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z style="height:11px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x><y style="height:4px;"></y></masonry-track>
+  </div>
+  <div class="grid last" style="height:6px;">
+    <masonry-track><z style="height:1px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><y style="height:6px;"></y></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:8px;"></y></masonry-track>
+    <masonry-track><z style="height:8px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:2px;"></y><y style="height:4px;"></y></masonry-track>
+    <masonry-track><z style="height:4px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:6px;"></y></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><z style="height:8px;"></z></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><y style="height:8px;"></y></masonry-track>
+    <masonry-track><z style="height:4px;"></z></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><x></x><y style="height:1px;"></y></masonry-track>
+    <masonry-track><y style="height:2px;"></y></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:8px;"></y></masonry-track>
+    <masonry-track><z style="height:8px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:1px;"></y><x></x></masonry-track>
+    <masonry-track><z style="height:4px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z style="height:8px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x><y style="height:1px;"></y></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z style="height:4px;"></z></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><y style="height:8px;"></y></masonry-track>
+  </div>
+  <div class="grid last" style="height:1px;">
+    <masonry-track></masonry-track>
+    <masonry-track></masonry-track>
+    <masonry-track><y style="height:1px;"></y></masonry-track>
+  </div>
+</div>
+<script>
+let elts = document.querySelectorAll(".columns");
+let heights = [ 78, 68, 58, 48, 38, 28, 18, 12, 11, 8 ];
+for (let i = 0; i < heights.length; ++i) {
+  elts[i].style.height = heights[i] + "px";
+}
+</script>
+</wrapper>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-001.html
new file mode 100644
index 00000000000..69182c5425e
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-001.html
@@ -0,0 +1,79 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout fragmentation</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-fragmentation-001-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+.columns {
+  width: 330px;
+  columns: 6;
+  column-fill: auto;
+  column-gap: 1px;
+  background-color: rgba(80,80,80,.2);
+  margin-bottom: 10px;
+}
+.columns:nth-child(2n) {
+  background-color: rgba(10,100,10,.5);
+}
+.grid {
+  display: grid;
+  grid-template-columns: 10px 15px 20px;
+  grid-template-rows: masonry;
+  border: 1px solid;
+  gap: 2px;
+}
+x {
+  background: cyan;
+  height: 5px;
+  break-inside: avoid;
+}
+x:nth-child(4n) {
+  background: blue;
+  height: 10px;
+  break-inside: auto;
+}
+x:nth-child(5n) {
+  background: pink;
+  height: 12px;
+  break-inside: avoid;
+}
+</style></head>
+<body>
+<wrapper style="display:none">
+<div style="display:none">
+<div class="columns">
+  <div class="grid">
+    <x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x>
+    <x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x>
+  </div>
+</div>
+</div>
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let tmplt = document.querySelectorAll(".columns")[0];
+let heights = [ 78, 68, 58, 48, 38, 28, 18, 12, 11, 8 ];
+for (let h of heights) {
+  let e = tmplt.cloneNode(true);
+  e.style.height = h + "px";
+  wrapper.appendChild(e);
+}
+wrapper.style.display="";
+</script>
+</wrapper>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-002-ref.html
new file mode 100644
index 00000000000..ea21350f437
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-002-ref.html
@@ -0,0 +1,132 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout fragmentation</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+.columns {
+  width: 330px;
+  columns: 6;
+  column-fill: auto;
+  column-gap: 1px;
+  background-color: rgba(80,80,80,.2);
+  margin-bottom: 10px;
+}
+.columns:nth-child(2n) {
+  background-color: rgba(10,100,10,.5);
+}
+.grid {
+  display: flow-root;
+  border: 1px solid;
+  gap: 2px;
+}
+.first { border-bottom-width:0; height:calc(100% - 1px); }
+.middle { border-top-width:0; border-bottom-width:0; height:100%; }
+.last { border-top-width:0; }
+x {
+  background: cyan;
+  height: 5px;
+}
+y {
+  background: blue;
+  height: 10px;
+}
+.c1 { width: 27px; }
+.c2 { width: 37px; }
+s { height: 10px; }
+z {
+  background: pink;
+  height: 12px;
+}
+masonry-track {
+  float: left;
+  height: 100%;
+  gap: 2px;
+}
+x,y,s,z,masonry-track { display: block; }
+masonry-track > * { margin-bottom:2px; }
+masonry-track.last > :last-child { margin-bottom:0; }
+masonry-track:nth-child(1) { width: 10px; }
+masonry-track:nth-child(2) { width: 15px; margin-left:2px; }
+masonry-track:nth-child(3) { width: 20px; margin-left:2px; }
+</style></head>
+<body>
+<wrapper>
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y class="c1"></y><x></x><y class="c1"></y><x></x></masonry-track>
+    <masonry-track><x></x><s></s><x></x><s style="margin-bottom:6px"></s><y class="c2" style="height:5px"></y></masonry-track>
+    <masonry-track><x></x><z></z><x></x><z></z></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><x></x><x></x><s style="height:5px"></s><y class="c1"></y><z class="c1"></z><y class="c1" style="height:1px"></y></masonry-track>
+    <masonry-track><y class="c2" style="height:5px"></y><z></z></masonry-track>
+    <masonry-track><s style="height:5px"></s><x></x><x></x><x></x><x></x><x></x><x></x></masonry-track>
+  </div>
+  <div class="grid last" style="height:9px">
+    <masonry-track><y style="height:9px" class="c1"></y></masonry-track>
+    <masonry-track></masonry-track>
+    <masonry-track></masonry-track>
+  </div>
+</div>
+
+<div class="columns">
+  <div class="grid first">
+    <masonry-track><x></x><y class="c1"></masonry-track>
+    <masonry-track><x></x></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z></z></masonry-track>
+    <masonry-track><x></x><y class="c2"></y></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><x></x><s style="height:5px"></s><y style="height:4px" class="c1"></y></masonry-track>
+    <masonry-track><z></z></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><y style="height:6px" class="c1"></y><y class="c1"></y></masonry-track>
+    <masonry-track></masonry-track>
+    <masonry-track><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z></z></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+  </div>
+  <div class="grid middle">
+    <masonry-track><z class="c1"></z><y style="height:4px" class="c1"></y></masonry-track>
+    <masonry-track></masonry-track>
+    <masonry-track><x></x><x></x></masonry-track>
+  </div>
+  <div class="grid last" style="height:6px;">
+    <masonry-track><y style="height:6px" class="c1"></y></masonry-track>
+    <masonry-track></masonry-track>
+    <masonry-track></masonry-track>
+  </div>
+</div>
+<script>
+let elts = document.querySelectorAll(".columns");
+let heights = [ 48, 18 ];
+for (let i = 0; i < heights.length; ++i) {
+  elts[i].style.height = heights[i] + "px";
+}
+</script>
+</wrapper>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-002.html
new file mode 100644
index 00000000000..01c4de00b56
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-002.html
@@ -0,0 +1,80 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout fragmentation</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-fragmentation-002-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+.columns {
+  width: 330px;
+  columns: 6;
+  column-fill: auto;
+  column-gap: 1px;
+  background-color: rgba(80,80,80,.2);
+  margin-bottom: 10px;
+}
+.columns:nth-child(2n) {
+  background-color: rgba(10,100,10,.5);
+}
+.grid {
+  display: grid;
+  grid-template-columns: 10px 15px 20px;
+  grid-template-rows: masonry;
+  border: 1px solid;
+  gap: 2px;
+}
+x {
+  background: cyan;
+  height: 5px;
+  break-inside: avoid;
+}
+x:nth-child(4n) {
+  grid-column: span 2;
+  background: blue;
+  height: 10px;
+  break-inside: auto;
+}
+x:nth-child(5n) {
+  background: pink;
+  height: 12px;
+  break-inside: avoid;
+}
+</style></head>
+<body>
+<wrapper style="display:none">
+<div style="display:none">
+<div class="columns">
+  <div class="grid">
+    <x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x>
+    <x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x>
+  </div>
+</div>
+</div>
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let tmplt = document.querySelectorAll(".columns")[0];
+let heights = [ 48, 18 ];
+for (let h of heights) {
+  let e = tmplt.cloneNode(true);
+  e.style.height = h + "px";
+  wrapper.appendChild(e);
+}
+wrapper.style.display="";
+</script>
+</wrapper>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-003-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-003-ref.html
new file mode 100644
index 00000000000..9d1036dfebd
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-003-ref.html
@@ -0,0 +1,114 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Grid axis fragmentation with column masonry layout</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+
+.columns {
+  columns: 3;
+  column-fill: auto;
+  background: lightgrey;
+  margin-bottom: 15px;
+}
+
+.grid {
+  display: grid;
+  grid: 20px auto 30px / auto;
+  border: solid;
+  border-width: 3px 1px 7px 5px;
+  padding: 1px 3px 5px 7px;
+  gap: 1px 5px;
+}
+
+x {
+  background: cyan;
+  min-width: 20px;
+  min-height: 10px;
+}
+y {
+  background: blue;
+  width: 35px;
+}
+z {
+  background: gray;
+  width: 40px;
+}
+masonry-track {
+  display: grid;
+  justify-content: start;
+  column-gap: 5px;
+}
+</style>
+</head>
+<body>
+<wrapper style="display:none">
+<div class="columns" style="height:90px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:68px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:48px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:38px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:28px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:18px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+</wrapper>
+
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let grids = document.querySelectorAll(".grid");
+for (let e of grids) {
+  for (let track of e.children) {
+    track.style.gridTemplateColumns = "repeat(" + track.children.length + ",auto)";
+  }
+}
+wrapper.style.display="";
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-003.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-003.html
new file mode 100644
index 00000000000..fe150e7f838
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-003.html
@@ -0,0 +1,76 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Grid axis fragmentation with column masonry layout</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-fragmentation-003-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+
+.columns {
+  columns: 3;
+  column-fill: auto;
+  background: lightgrey;
+  margin-bottom: 15px;
+}
+
+.grid {
+  display: grid;
+  grid: 20px auto 30px / masonry;
+  border: solid;
+  border-width: 3px 1px 7px 5px;
+  padding: 1px 3px 5px 7px;
+  gap: 1px 5px;
+}
+
+.grid > * {
+  background: cyan;
+  min-width: 20px;
+  min-height: 10px;
+}
+.grid > :nth-child(4n) {
+  background: blue;
+  width: 35px;
+}
+.grid > :nth-child(3n) {
+  background: gray;
+  width: 40px;
+}
+</style>
+</head>
+<body>
+<wrapper style="display:none">
+<div style="display:none">
+<div class="columns">
+  <div class="grid">
+    <x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x>
+  </div>
+</div>
+</div>
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let tmplt = document.querySelectorAll(".columns")[0];
+let heights = [ 90, 68, 48, 38, 28, 18 ];
+for (let h of heights) {
+  let e = tmplt.cloneNode(true);
+  e.style.height = h + "px";
+  wrapper.appendChild(e);
+}
+wrapper.style.display="";
+</script>
+</wrapper>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-004-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-004-ref.html
new file mode 100644
index 00000000000..10246dac421
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-004-ref.html
@@ -0,0 +1,114 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Grid axis fragmentation with column masonry layout</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+
+.columns {
+  columns: 3;
+  column-fill: auto;
+  background: lightgrey;
+  margin-bottom: 15px;
+}
+
+.grid {
+  display: grid;
+  grid: 20px auto 30px / auto;
+  border: solid;
+  border-width: 3px 1px 7px 5px;
+  padding: 1px 3px 5px 7px;
+  gap: 1px 5px;
+}
+
+x {
+  background: cyan;
+  min-width: 20px;
+  min-height: 10px;
+}
+y {
+  background: blue;
+  width: 35px;
+}
+z {
+  background: gray;
+  width: 40px;
+}
+masonry-track {
+  display: grid;
+  justify-content: end;
+  column-gap: 5px;
+}
+</style>
+</head>
+<body>
+<wrapper style="display:none">
+<div class="columns" style="height:90px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:68px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:48px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:38px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:28px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:18px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+</wrapper>
+
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let grids = document.querySelectorAll(".grid");
+for (let e of grids) {
+  for (let track of e.children) {
+    track.style.gridTemplateColumns = "repeat(" + track.children.length + ",auto)";
+  }
+}
+wrapper.style.display="";
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-004.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-004.html
new file mode 100644
index 00000000000..ddfc1bb331f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-004.html
@@ -0,0 +1,77 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Grid axis fragmentation with column masonry layout</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-fragmentation-004-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+
+.columns {
+  columns: 3;
+  column-fill: auto;
+  background: lightgrey;
+  margin-bottom: 15px;
+}
+
+.grid {
+  display: grid;
+  grid: 20px auto 30px / masonry;
+  justify-tracks: end;
+  border: solid;
+  border-width: 3px 1px 7px 5px;
+  padding: 1px 3px 5px 7px;
+  gap: 1px 5px;
+}
+
+.grid > * {
+  background: cyan;
+  min-width: 20px;
+  min-height: 10px;
+}
+.grid > :nth-child(4n) {
+  background: blue;
+  width: 35px;
+}
+.grid > :nth-child(3n) {
+  background: gray;
+  width: 40px;
+}
+</style>
+</head>
+<body>
+<wrapper style="display:none">
+<div style="display:none">
+<div class="columns">
+  <div class="grid">
+    <x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x>
+  </div>
+</div>
+</div>
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let tmplt = document.querySelectorAll(".columns")[0];
+let heights = [ 90, 68, 48, 38, 28, 18 ];
+for (let h of heights) {
+  let e = tmplt.cloneNode(true);
+  e.style.height = h + "px";
+  wrapper.appendChild(e);
+}
+wrapper.style.display="";
+</script>
+</wrapper>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-005-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-005-ref.html
new file mode 100644
index 00000000000..e059f414dc7
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-005-ref.html
@@ -0,0 +1,114 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Grid axis fragmentation with column masonry layout</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+
+.columns {
+  columns: 3;
+  column-fill: auto;
+  background: lightgrey;
+  margin-bottom: 15px;
+}
+
+.grid {
+  display: grid;
+  grid: 20px auto 30px / auto;
+  border: solid;
+  border-width: 3px 1px 7px 5px;
+  padding: 1px 3px 5px 7px;
+  gap: 1px 5px;
+}
+
+x {
+  background: cyan;
+  min-width: 20px;
+  min-height: 10px;
+}
+y {
+  background: blue;
+  width: 35px;
+}
+z {
+  background: gray;
+  width: 40px;
+}
+masonry-track {
+  display: grid;
+  justify-content: space-between;
+  column-gap: 5px;
+}
+</style>
+</head>
+<body>
+<wrapper style="display:none">
+<div class="columns" style="height:90px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:68px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:48px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:38px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:28px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:18px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+</wrapper>
+
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let grids = document.querySelectorAll(".grid");
+for (let e of grids) {
+  for (let track of e.children) {
+    track.style.gridTemplateColumns = "repeat(" + track.children.length + ",auto)";
+  }
+}
+wrapper.style.display="";
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-005.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-005.html
new file mode 100644
index 00000000000..8315b8f2b55
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-005.html
@@ -0,0 +1,77 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Grid axis fragmentation with column masonry layout</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-fragmentation-005-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+
+.columns {
+  columns: 3;
+  column-fill: auto;
+  background: lightgrey;
+  margin-bottom: 15px;
+}
+
+.grid {
+  display: grid;
+  grid: 20px auto 30px / masonry;
+  justify-tracks: space-between;
+  border: solid;
+  border-width: 3px 1px 7px 5px;
+  padding: 1px 3px 5px 7px;
+  gap: 1px 5px;
+}
+
+.grid > * {
+  background: cyan;
+  min-width: 20px;
+  min-height: 10px;
+}
+.grid > :nth-child(4n) {
+  background: blue;
+  width: 35px;
+}
+.grid > :nth-child(3n) {
+  background: gray;
+  width: 40px;
+}
+</style>
+</head>
+<body>
+<wrapper style="display:none">
+<div style="display:none">
+<div class="columns">
+  <div class="grid">
+    <x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x>
+  </div>
+</div>
+</div>
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let tmplt = document.querySelectorAll(".columns")[0];
+let heights = [ 90, 68, 48, 38, 28, 18 ];
+for (let h of heights) {
+  let e = tmplt.cloneNode(true);
+  e.style.height = h + "px";
+  wrapper.appendChild(e);
+}
+wrapper.style.display="";
+</script>
+</wrapper>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-006-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-006-ref.html
new file mode 100644
index 00000000000..5df37376190
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-006-ref.html
@@ -0,0 +1,118 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Grid axis fragmentation with column masonry layout</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+
+.columns {
+  columns: 3;
+  column-fill: auto;
+  background: lightgrey;
+  margin-bottom: 15px;
+}
+
+.grid {
+  display: grid;
+  grid: 20px auto 30px / auto;
+  border: solid;
+  border-width: 3px 1px 7px 5px;
+  padding: 1px 3px 5px 7px;
+  gap: 1px 5px;
+}
+
+x {
+  background: cyan;
+  min-width: 20px;
+  min-height: 10px;
+}
+y {
+  background: blue;
+  width: 35px;
+}
+z {
+  background: gray;
+  width: 40px;
+}
+masonry-track {
+  display: grid;
+  justify-content: stretch;
+  column-gap: 5px;
+}
+</style>
+</head>
+<body>
+<wrapper style="display:none">
+<div class="columns" style="height:90px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:68px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:48px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:38px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:28px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+<div class="columns" style="height:18px">
+  <div class="grid">
+    <masonry-track><x></x><y></y><y></y><x></x></masonry-track>
+    <masonry-track><x></x><x></x><x></x><z></z></masonry-track>
+    <masonry-track><z></z><z></z><x></x><z></z></masonry-track>
+  </div>
+</div>
+</wrapper>
+
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let grids = document.querySelectorAll(".grid");
+for (let e of grids) {
+  for (let track of e.children) {
+    var cols = "";
+    for (let item of track.children) {
+      if (item.tagName != "X") cols += "min-content "; else  cols += "auto ";
+    }
+    track.style.gridTemplateColumns = cols;
+  }
+}
+wrapper.style.display="";
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-006.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-006.html
new file mode 100644
index 00000000000..9dab0ddc9b6
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-fragmentation-006.html
@@ -0,0 +1,77 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Grid axis fragmentation with column masonry layout</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-fragmentation-006-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+wrapper {
+  display: block;
+  width: 600px;
+  height: 600px;
+  overflow: hidden;
+}
+
+.columns {
+  columns: 3;
+  column-fill: auto;
+  background: lightgrey;
+  margin-bottom: 15px;
+}
+
+.grid {
+  display: grid;
+  grid: 20px auto 30px / masonry;
+  justify-tracks: stretch;
+  border: solid;
+  border-width: 3px 1px 7px 5px;
+  padding: 1px 3px 5px 7px;
+  gap: 1px 5px;
+}
+
+.grid > * {
+  background: cyan;
+  min-width: 20px;
+  min-height: 10px;
+}
+.grid > :nth-child(4n) {
+  background: blue;
+  width: 35px;
+}
+.grid > :nth-child(3n) {
+  background: gray;
+  width: 40px;
+}
+</style>
+</head>
+<body>
+<wrapper style="display:none">
+<div style="display:none">
+<div class="columns">
+  <div class="grid">
+    <x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x><x></x>
+  </div>
+</div>
+</div>
+<script>
+let wrapper = document.querySelectorAll("wrapper")[0];
+let tmplt = document.querySelectorAll(".columns")[0];
+let heights = [ 90, 68, 48, 38, 28, 18 ];
+for (let h of heights) {
+  let e = tmplt.cloneNode(true);
+  e.style.height = h + "px";
+  wrapper.appendChild(e);
+}
+wrapper.style.display="";
+</script>
+</wrapper>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-gap-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-gap-001-ref.html
new file mode 100644
index 00000000000..5e92a681a0d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-gap-001-ref.html
@@ -0,0 +1,42 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with definite `gap` in both axes</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-template-columns:  auto min-content repeat(2,auto);
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item>1</item>
+  <item style="padding:0; place-self:start; min-width:0">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="order:1; width:0; margin-right:-23px; margin-top:-37px; align-self:start">5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-gap-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-gap-001.html
new file mode 100644
index 00000000000..17873d1e96c
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-gap-001.html
@@ -0,0 +1,45 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with definite `gap` in both axes</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-gap-001-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-template-columns:  repeat(4,auto);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item>1</item>
+  <item style="padding:0">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-content-baseline-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-content-baseline-001-ref.html
new file mode 100644
index 00000000000..cdb6d4fdf8f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-content-baseline-001-ref.html
@@ -0,0 +1,88 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: align-content:baseline/last baseline</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+    color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+.grid {
+  float: left;
+  display: grid;
+  grid: auto / repeat(4, auto);
+  border: 2px solid;
+  padding: 1px;
+  margin: 1px;
+}
+.c {
+  grid: repeat(4, auto) / auto;
+}
+
+span {
+  background: lime;
+  border: 1px solid black;
+}
+
+span:nth-child(1) { font-size:15px; }
+span:nth-child(2) { font-size:30px; }
+span:nth-child(3) { font-size:10px; }
+.pbs { padding-block-start: 15px; margin-block-start: 5px; }
+.pbe { padding-block-end: 7px; margin-block-end: 3px; }
+
+.fb { align-content:baseline; align-self:self-start; justify-self:self-start; }
+.lb { align-content:last baseline; align-self:self-end; justify-self:self-end; }
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vl { writing-mode: vertical-lr; text-orientation: sideways; }
+.vr { writing-mode: vertical-rl; text-orientation: sideways; }
+.vlr { writing-mode: vertical-lr; direction:rtl; text-orientation: sideways; }
+.vrl { writing-mode: vertical-rl; direction:ltr; text-orientation: sideways; }
+
+</style>
+</head>
+<body>
+
+<div class="grid hl"><span class="fb">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid hl"><span class="fb pbe">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid vl"><span class="fb">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid vl"><span class="fb pbs">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid vr"><span class="fb">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid vr"><span class="fb pbe">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+
+<br clear="all">
+
+<div class="grid hl"><span class="fb" style="padding-top:27px">A<br>B</span><span class="lb">M<br>N</span></div>
+<div class="grid hl"><span class="fb pbe" style="padding-top:27px">A<br>B</span><span class="lb" style="margin-bottom:7px">M<br>N</span></div>
+<div class="grid vl"><span class="fb" style="padding-left:18px">A<br>B</span><span class="lb">M<br>N</span></div>
+<div class="grid vl"><span class="fb pbs">A<br>B</span><span class="lb" style="padding-left:2px">M<br>N</span></div>
+<div class="grid vr"><span class="fb" style="padding-right:27px">A<br>B</span><span class="lb">M<br>N</span></div>
+<div class="grid vr"><span class="fb pbe" style="padding-right:27px">A<br>B</span><span class="lb" style="margin-left:7px">M<br>N</span></div>
+
+<br clear="all">
+
+<div class="grid c hl"><span class="fb vl">A<br>B</span><span class="fb vl">M<br>N</span><span class="fb vl">X<br>Z</span></div>
+<div class="grid c hl"><span class="fb vl pbe">A<br>B</span><span class="fb vl">M<br>N</span><span class="fb vl">X<br>Z</span></div>
+<div class="grid c vl"><span class="fb hl">A<br>B</span><span class="fb hl">M<br>N</span><span class="fb hl">X<br>Z</span></div>
+<div class="grid c vl" style="inline-size:100px"><span class="fb hl pbs">A<br>B</span><span class="fb hl">M<br>N</span><span class="fb hl">X<br>Z</span></div>
+<div class="grid c vr"><span class="fb hl">A<br>B</span><span class="fb hl">M<br>N</span><span class="fb hl">X<br>Z</span></div>
+<div class="grid c vr"><span class="fb hl pbe">A<br>B</span><span class="fb hl">M<br>N</span><span class="fb hl">X<br>Z</span></div>
+
+<br clear="all">
+
+<div class="grid c hl"><span class="fb vl" style="padding-left:18px">A<br>B</span><span class="vl">M<br>N</span></div>
+<div class="grid c hl"><span class="fb vl pbe" style="padding-left:18px">A<br>B</span><span class="vl">M<br>N</span></div>
+<div class="grid c vl"><span class="fb hl" style="padding-top:27px">A<br>B</span><span class="hl">M<br>N</span></div>
+<div class="grid c vl"><span class="fb hl pbs" style="padding-top:22px">A<br>B</span><span class="hl">M<br>N</span></div>
+<div class="grid c vr"><span class="fb hl" style="padding-top:27px">A<br>B</span><span class="hl">M<br>N</span></div>
+<div class="grid c vr" style="inline-size:100px"><span class="hl pbe" style="justify-self:start; padding-top:27px">A<br>B</span><span class="fb hl">M<br>N</span></div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-content-baseline-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-content-baseline-001.html
new file mode 100644
index 00000000000..60d11653b3f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-content-baseline-001.html
@@ -0,0 +1,90 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: align-content:baseline/last baseline</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-align-3/#baseline-align-content">
+  <link rel="match" href="masonry-grid-item-content-baseline-001-ref.html">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+    color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+.grid {
+  float: left;
+  display: grid;
+  grid: masonry / repeat(4, auto);
+  border: 2px solid;
+  padding: 1px;
+  margin: 1px;
+}
+.c {
+  grid: repeat(4, auto) / masonry;
+}
+
+span {
+  background: lime;
+  border: 1px solid black;
+}
+
+span:nth-child(1) { font-size:15px; }
+span:nth-child(2) { font-size:30px; }
+span:nth-child(3) { font-size:10px; }
+.pbs { padding-block-start: 15px; margin-block-start: 5px; }
+.pbe { padding-block-end: 7px; margin-block-end: 3px; }
+
+.fb { align-content:baseline; }
+.lb { align-content:last baseline; }
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vl { writing-mode: vertical-lr; text-orientation: sideways; }
+.vr { writing-mode: vertical-rl; text-orientation: sideways; }
+.vlr { writing-mode: vertical-lr; direction:rtl; text-orientation: sideways; }
+.vrl { writing-mode: vertical-rl; direction:ltr; text-orientation: sideways; }
+
+</style>
+</head>
+<body>
+
+<div class="grid hl"><span class="fb">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid hl"><span class="fb pbe">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid vl"><span class="fb">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid vl"><span class="fb pbs">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid vr"><span class="fb">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+<div class="grid vr"><span class="fb pbe">A<br>B</span><span class="fb">M<br>N</span><span class="fb">X<br>Z</span></div>
+
+<br clear="all">
+
+<div class="grid hl"><span class="lb">A<br>B</span><span class="lb">M<br>N</span></div>
+<div class="grid hl"><span class="lb pbe">A<br>B</span><span class="lb">M<br>N</span></div>
+<div class="grid vl"><span class="lb">A<br>B</span><span class="lb">M<br>N</span></div>
+<div class="grid vl"><span class="lb pbs">A<br>B</span><span class="lb">M<br>N</span></div>
+<div class="grid vr"><span class="lb">A<br>B</span><span class="lb">M<br>N</span></div>
+<div class="grid vr"><span class="lb pbe">A<br>B</span><span class="lb">M<br>N</span></div>
+
+<br clear="all">
+
+<div class="grid c hl"><span class="fb vl">A<br>B</span><span class="fb vl">M<br>N</span><span class="fb vl">X<br>Z</span></div>
+<div class="grid c hl"><span class="fb vl pbe">A<br>B</span><span class="fb vl">M<br>N</span><span class="fb vl">X<br>Z</span></div>
+<div class="grid c vl"><span class="fb hl">A<br>B</span><span class="fb hl">M<br>N</span><span class="fb hl">X<br>Z</span></div>
+<div class="grid c vl" style="inline-size:100px"><span class="fb hl pbs">A<br>B</span><span class="fb hl">M<br>N</span><span class="fb hl">X<br>Z</span></div>
+<div class="grid c vr"><span class="fb hl">A<br>B</span><span class="fb hl">M<br>N</span><span class="fb hl">X<br>Z</span></div>
+<div class="grid c vr"><span class="fb hl pbe">A<br>B</span><span class="fb hl">M<br>N</span><span class="fb hl">X<br>Z</span></div>
+
+<br clear="all">
+
+<div class="grid c hl"><span class="lb vl">A<br>B</span><span class="lb vl">M<br>N</span></div>
+<div class="grid c hl"><span class="lb vl pbe">A<br>B</span><span class="lb vl">M<br>N</span></div>
+<div class="grid c vl"><span class="lb hl">A<br>B</span><span class="lb hl">M<br>N</span></div>
+<div class="grid c vl"><span class="lb hl pbs">A<br>B</span><span class="lb hl">M<br>N</span></div>
+<div class="grid c vr"><span class="lb hl">A<br>B</span><span class="lb hl">M<br>N</span></div>
+<div class="grid c vr" style="inline-size:100px"><span class="lb hl pbe">A<br>B</span><span class="lb hl">M<br>N</span></div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-001-ref.html
new file mode 100644
index 00000000000..817f19ff84e
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-001-ref.html
@@ -0,0 +1,123 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: align-self/justify-self:baseline/last baseline</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+    color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+body { width:600px; height:600px; border:1px solid; box-sizing:border-box; }
+
+.grid {
+  float: left;
+  display: grid;
+  grid: auto / repeat(4, auto);
+  place-items: start;
+  padding-block-start: 1px;
+  margin-left: 1px;
+  border:1px solid;
+}
+.c {
+  grid: repeat(4, auto) / auto;
+}
+
+span {
+  text-decoration: underline lime;
+  text-decoration-thickness: 1px;
+  text-underline-offset: 0;
+  text-decoration-skip-ink: none;
+  background: grey;
+}
+.central > span { text-decoration-line: line-through; }
+x { display:block; visibility:hidden; }
+span:nth-child(1) { font-size:10px; }
+span:nth-child(2) { font-size:15px; }
+span:nth-child(3) { font-size:25px; }
+span:nth-child(4) { font-size:30px; }
+.pbe { padding-block-end:20px; }
+.pbs { padding-block-start:20px; }
+
+.fb { align-self:baseline; }
+.lb { align-self:last baseline; }
+
+.jfb { justify-self:baseline; }
+.jlb { justify-self:last baseline; }
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; }
+.swr { writing-mode: sideways-rl; }
+
+</style>
+</head>
+<body>
+
+<div class="grid"><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span></div>
+<div class="grid"><span class="fb hl pbe">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span></div>
+<div class="grid vll central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vll central"><span class="fb pbs">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vlr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vrr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vrr central"><span class="fb pbe">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vrl central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid swl central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid swr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid"><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid"><span class="lb hl pbe"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrl central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid c central"><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span></div>
+<div class="grid c central"><span class="jfb vll pbe">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span></div>
+<div class="grid c vll"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<!-- TODO: baseline alignment affects intrinsic inline size
+<div class="grid c vll"><span class="jfb hl pbs">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+-->
+<div class="grid c vll" style="height:80px"><span class="jfb hl pbs">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<!-- TODO
+<div class="grid c vrr"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid c vrr"><span class="jfb hl pbe">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid c swl"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+-->
+<div class="grid c swr"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid"><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid"><span class="lb hl pbe"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid vlr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrl central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrl central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-001.html
new file mode 100644
index 00000000000..bb486d983d9
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-001.html
@@ -0,0 +1,125 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: align-self/justify-self:baseline/last baseline</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-align-3/#baseline-align-self">
+  <link rel="match" href="masonry-grid-item-self-baseline-001-ref.html">
+  <style>
+html,body {
+    color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+body { width:600px; height:600px; border:1px solid; box-sizing:border-box; }
+
+.grid {
+  float: left;
+  display: grid;
+  grid: masonry / repeat(4, auto);
+  place-items: start;
+  padding-block-start: 1px;
+  margin-left: 1px;
+  border:1px solid;
+}
+.c {
+  grid: repeat(4, auto) / masonry;
+}
+
+span {
+  text-decoration: underline lime;
+  text-decoration-thickness: 1px;
+  text-underline-offset: 0;
+  text-decoration-skip-ink: none;
+  background: grey;
+}
+.central > span { text-decoration-line: line-through; }
+x { display:block; visibility:hidden; }
+span:nth-child(1) { font-size:10px; }
+span:nth-child(2) { font-size:15px; }
+span:nth-child(3) { font-size:25px; }
+span:nth-child(4) { font-size:30px; }
+.pbe { padding-block-end:20px; }
+.pbs { padding-block-start:20px; }
+
+.fb { align-self:baseline; }
+.lb { align-self:last baseline; }
+
+.jfb { justify-self:baseline; }
+.jlb { justify-self:last baseline; }
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; }
+.swr { writing-mode: sideways-rl; }
+
+</style>
+</head>
+<body>
+
+<div class="grid"><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span></div>
+<div class="grid"><span class="fb hl pbe">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span></div>
+<div class="grid vll central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vll central"><span class="fb pbs">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vlr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vrr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vrr central"><span class="fb pbe">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vrl central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid swl central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid swr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid"><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid"><span class="lb hl pbe"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrl central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid c central"><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span></div>
+<div class="grid c central"><span class="jfb vll pbe">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span></div>
+<div class="grid c vll"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<!-- TODO: baseline alignment affects intrinsic inline size
+<div class="grid c vll"><span class="jfb hl pbs">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+-->
+<div class="grid c vll" style="height:80px"><span class="jfb hl pbs">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<!-- TODO
+<div class="grid c vrr"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid c vrr"><span class="jfb hl pbe">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid c swl"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+-->
+<div class="grid c swr"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid"><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid"><span class="lb hl pbe"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid vlr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrl central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrl central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002a-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002a-ref.html
new file mode 100644
index 00000000000..ddce4e34a71
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002a-ref.html
@@ -0,0 +1,102 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: align-self/justify-self:baseline/last baseline</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+    color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+body { width:600px; height:600px; border:1px solid; box-sizing:border-box; }
+
+.grid {
+  float: left;
+  display: grid;
+  grid: auto / repeat(4, auto);
+  place-items: start;
+  padding-block-start: 1px;
+  margin-left: 1px;
+  border:1px solid;
+  height: 100px;
+  width: 100px;
+}
+.c { grid: repeat(4, auto) / auto; }
+.ae { align-content: end; }
+.je { justify-content: end; }
+
+span {
+  text-decoration: underline lime;
+  text-decoration-thickness: 1px;
+  text-underline-offset: 0;
+  text-decoration-skip-ink: none;
+  background: grey;
+}
+.central > span { text-decoration-line: line-through; }
+x { display:block; visibility:hidden; }
+span:nth-child(1) { font-size:10px; }
+span:nth-child(2) { font-size:15px; }
+span:nth-child(3) { font-size:25px; }
+span:nth-child(4) { font-size:30px; }
+.pbe { padding-block-end:20px; }
+.pbs { padding-block-start:20px; }
+
+.fb { align-self:baseline; }
+.lb { align-self:last baseline; }
+
+.jfb { justify-self:baseline; }
+.jlb { justify-self:last baseline; }
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; }
+.swr { writing-mode: sideways-rl; }
+
+</style>
+</head>
+<body>
+
+<div class="grid ae"><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span></div>
+<div class="grid ae"><span class="fb hl pbe">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span></div>
+<div class="grid ae vll central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid ae vll central"><span class="fb pbs">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid ae vlr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid ae vrr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid ae vrr central"><span class="fb pbe">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid ae vrl central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid ae swl central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid ae swr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid"><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid"><span class="lb hl pbe"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid vrl central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid je c central"><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span></div>
+<div class="grid je c central"><span class="jfb vll pbe">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid je c vll"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid je c vll"><span class="jfb hl pbs">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002a.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002a.html
new file mode 100644
index 00000000000..f89217c68e0
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002a.html
@@ -0,0 +1,105 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: align-self/justify-self:baseline/last baseline</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-align-3/#baseline-align-self">
+  <link rel="match" href="masonry-grid-item-self-baseline-002a-ref.html">
+  <style>
+html,body {
+    color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+body { width:600px; height:600px; border:1px solid; box-sizing:border-box; }
+
+.grid {
+  float: left;
+  display: grid;
+  grid: masonry / repeat(4, auto);
+  place-items: start;
+  padding-block-start: 1px;
+  margin-left: 1px;
+  border:1px solid;
+  align-tracks: end;
+  justify-tracks: end;
+  masonry-auto-flow: next;
+  height: 100px;
+  width: 100px;
+}
+.c { grid: repeat(4, auto) / masonry; }
+
+span {
+  text-decoration: underline lime;
+  text-decoration-thickness: 1px;
+  text-underline-offset: 0;
+  text-decoration-skip-ink: none;
+  background: grey;
+}
+.central > span { text-decoration-line: line-through; }
+x { display:block; background:yellow; visibility:hidden; }
+span:nth-child(1) { font-size:10px; }
+span:nth-child(2) { font-size:15px; }
+span:nth-child(3) { font-size:25px; }
+span:nth-child(4) { font-size:30px; }
+.pbe { padding-block-end:20px; }
+.pbs { padding-block-start:20px; }
+
+.fb { align-self:baseline; }
+.lb { align-self:last baseline; }
+
+.jfb { justify-self:baseline; }
+.jlb { justify-self:last baseline; }
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; }
+.swr { writing-mode: sideways-rl; }
+
+</style>
+</head>
+<body>
+
+<div class="grid"><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span></div>
+<div class="grid"><span class="fb hl pbe">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span><span class="fb hl">F<br><x>x</x></span></div>
+<div class="grid vll central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vll central"><span class="fb pbs">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vlr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid vrr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vrr central"><span class="fb pbe">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid vrl central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid swl central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+<div class="grid swr central"><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span><span class="fb">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid"><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid"><span class="lb hl pbe"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid vrl central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid c central"><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span></div>
+<div class="grid c central"><span class="jfb vll pbe">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span><span class="jfb vll">F<br><x>x</x></span></div>
+
+<br clear="all">
+
+<div class="grid c vll"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid c vll"><span class="jfb hl pbs">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002b-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002b-ref.html
new file mode 100644
index 00000000000..44d8266436e
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002b-ref.html
@@ -0,0 +1,97 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: align-self/justify-self:baseline/last baseline</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+    color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+body { width:600px; height:600px; border:1px solid; box-sizing:border-box; }
+
+.grid {
+  float: left;
+  display: grid;
+  grid: auto / repeat(4, auto);
+  place-items: start;
+  padding-block-start: 1px;
+  margin-left: 1px;
+  border:1px solid;
+  height: 100px;
+  width: 100px;
+}
+.c { grid: repeat(4, auto) / auto; }
+.ae { align-content: end; }
+.je { justify-content: end; }
+
+span {
+  text-decoration: underline lime;
+  text-decoration-thickness: 1px;
+  text-underline-offset: 0;
+  text-decoration-skip-ink: none;
+  background: grey;
+}
+.central > span { text-decoration-line: line-through; }
+x { display:block; visibility:hidden; }
+span:nth-child(1) { font-size:10px; }
+span:nth-child(2) { font-size:15px; }
+span:nth-child(3) { font-size:25px; }
+span:nth-child(4) { font-size:30px; }
+.pbe { padding-block-end:20px; }
+.pbs { padding-block-start:20px; }
+
+.fb { align-self:baseline; }
+.lb { align-self:last baseline; }
+
+.jfb { justify-self:baseline; }
+.jlb { justify-self:last baseline; }
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; }
+.swr { writing-mode: sideways-rl; }
+
+</style>
+</head>
+<body>
+
+<!-- TODO: baseline alignment is wrong (bug 1633610)
+<div class="grid je c vrr"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid je c vrr"><span class="jfb hl pbe">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid je c swl"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+-->
+<div class="grid je c swr"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid ae"><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid"><span class="lb hl pbe"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrl central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid vrl central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002b.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002b.html
new file mode 100644
index 00000000000..eae435707d2
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-item-self-baseline-002b.html
@@ -0,0 +1,101 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: align-self/justify-self:baseline/last baseline</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-align-3/#baseline-align-self">
+  <link rel="match" href="masonry-grid-item-self-baseline-002b-ref.html">
+  <style>
+html,body {
+    color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+body { width:600px; height:600px; border:1px solid; box-sizing:border-box; }
+
+.grid {
+  float: left;
+  display: grid;
+  grid: masonry / repeat(4, auto);
+  place-items: start;
+  padding-block-start: 1px;
+  margin-left: 1px;
+  border:1px solid;
+  align-tracks: end;
+  justify-tracks: end;
+  masonry-auto-flow: next;
+  height: 100px;
+  width: 100px;
+}
+.c { grid: repeat(4, auto) / masonry; }
+
+span {
+  text-decoration: underline lime;
+  text-decoration-thickness: 1px;
+  text-underline-offset: 0;
+  text-decoration-skip-ink: none;
+  background: grey;
+}
+.central > span { text-decoration-line: line-through; }
+x { display:block; background:yellow; visibility:hidden; }
+span:nth-child(1) { font-size:10px; }
+span:nth-child(2) { font-size:15px; }
+span:nth-child(3) { font-size:25px; }
+span:nth-child(4) { font-size:30px; }
+.pbe { padding-block-end:20px; }
+.pbs { padding-block-start:20px; }
+
+.fb { align-self:baseline; }
+.lb { align-self:last baseline; }
+
+.jfb { justify-self:baseline; }
+.jlb { justify-self:last baseline; }
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; }
+.swr { writing-mode: sideways-rl; }
+
+</style>
+</head>
+<body>
+
+<!-- TODO: baseline alignment is wrong (bug 1633610)
+<div class="grid c vrr"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid c vrr"><span class="jfb hl pbe">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+<div class="grid c swl"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+-->
+<div class="grid c swr"><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span><span class="jfb hl">F<br><x>x</x></span></div>
+
+<div class="grid"><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid"><span class="lb hl pbe"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span><span class="lb hl"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vll central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrr central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vlr central"><span class="lb pbs"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid vrl central"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+<br clear="all">
+
+<div class="grid vrl central"><span class="lb pbe"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swl"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+<div class="grid swr"><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span><span class="lb"><x>x</x><br>L</span></div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-001-ref.html
new file mode 100644
index 00000000000..c99b117f2ee
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-001-ref.html
@@ -0,0 +1,129 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Placement involving named lines</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+body,html { color:black; background:white; font-size:15px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: grid;
+  position: relative;
+  border: 1px solid;
+  grid-gap: 1px;
+  grid-auto-flow: dense;
+}
+.t1 {
+  grid-template-columns: 40px 40px 40px 60px 60px 60px 40px 40px 40px 40px 40px 40px;
+
+}
+.t2 {
+  grid-template-columns: 40px 40px 40px 40px 60px 60px 60px 40px 40px 40px 40px 40px;
+}
+
+x {
+  background: grey;
+  border: 1px solid;
+}
+y {
+  position: absolute;
+  border-top: 1px solid blue;
+  bottom:0;height:0;left:0;right:0;
+}
+
+  </style>
+</head>
+<body>
+
+<pre>grid-column-start:</pre>
+<div class="grid t1" style="padding-right:13px; border-right-width:5px">
+<x style="grid-column-start:4; background:grey"></x>
+<x style="grid-column-start:7">-1</x>
+<x style="grid-column-start:7">4</x>
+<x style="grid-column-start:6">-2</x>
+<x style="grid-column-start:5">-3</x>
+<x style="grid-column-start:4">-4</x>
+<x style="grid-column-start:3">-5</x>
+<x style="grid-column-start:5">A -1</x>
+<x style="grid-column-start:3">B -1</x>
+<x style="grid-column-start:4">A -2</x>
+<x style="grid-column-start:3">A -3</x>
+<x style="grid-column-start:2">A -4</x>
+<x style="grid-column-start:1">A -5</x>
+<x style="grid-column-start:4">A</x>
+<x style="grid-column-start:4">B</x>
+<x style="grid-column-start:4">A 1</x>
+<x style="grid-column-start:5">A 2</x>
+<x style="grid-column-start:8">A 3</x>
+<x style="grid-column-start:9">A 4</x>
+<x style="grid-column-start:10">A 5</x>
+<y style="grid-column-start:7; top:0"></y>
+<y style="grid-column-start:7; top:2px"></y>
+<y style="grid-column-start:6; top:4px"></y>
+<y style="grid-column-start:5; top:6px"></y>
+<y style="grid-column-start:4; top:8px"></y>
+<y style="grid-column-start:3; top:10px"></y>
+<y style="grid-column-start:5; top:12px"></y>
+<y style="grid-column-start:3; top:14px"></y>
+<y style="grid-column-start:4; top:16px"></y>
+<y style="grid-column-start:3; top:18px"></y>
+<y style="grid-column-start:2; top:20px"></y>
+<y style="grid-column-start:1; top:22px"></y>
+<y style="grid-column-start:4; top:24px"></y>
+<y style="grid-column-start:4; top:26px"></y>
+<y style="grid-column-start:4; top:28px"></y>
+<y style="grid-column-start:5; top:30px"></y>
+<y style="grid-column-start:8; top:32px"></y>
+<y style="grid-column-start:9; top:34px"></y>
+<y style="grid-column-start:10; top:36px"></y>
+</div>
+
+<pre>grid-column-end:</pre>
+<div class="grid t2" style="padding-left:13px;">
+<x style="grid-column-start:5; background:grey"></x>
+<x style="grid-column-start:7">-1</x>
+<x style="grid-column-start:7">4</x>
+<x style="grid-column-start:6">-2</x>
+<x style="grid-column-start:5">-3</x>
+<x style="grid-column-start:4">-4</x>
+<x style="grid-column-start:3">-5</x>
+<x style="grid-column-start:5">A -1</x>
+<x style="grid-column-start:3">B -1</x>
+<x style="grid-column-start:4">A -2</x>
+<x style="grid-column-start:3">A -3</x>
+<x style="grid-column-start:2">A -4</x>
+<x style="grid-column-start:1">A -5</x>
+<x style="grid-column-start:4">A</x>
+<x style="grid-column-start:5">B</x>
+<x style="grid-column-start:4">A 1</x>
+<x style="grid-column-start:5">A 2</x>
+<x style="grid-column-start:8">A 3</x>
+<x style="grid-column-start:9">A 4</x>
+<x style="grid-column-start:10">A 5</x>
+<y style="grid-column-end:8; top:0px"></y>
+<y style="grid-column-end:8; top:2px"></y>
+<y style="grid-column-end:4; top:4px"></y>
+<y style="grid-column-end:5; top:6px"></y>
+<y style="grid-column-end:6; top:8px"></y>
+<y style="grid-column-end:7; top:10px"></y>
+<y style="grid-column-end:6; top:12px"></y>
+<y style="grid-column-end:4; top:14px"></y>
+<y style="grid-column-end:5; top:16px"></y>
+<y style="grid-column-end:4; top:18px"></y>
+<y style="grid-column-end:3; top:20px"></y>
+<y style="grid-column-end:2; top:22px"></y>
+<y style="grid-column-end:5; top:24px"></y>
+<y style="grid-column-end:6; top:26px"></y>
+<y style="grid-column-end:5; top:28px"></y>
+<y style="grid-column-end:6; top:30px"></y>
+<y style="grid-column-end:9; top:32px"></y>
+<y style="grid-column-end:10; top:34px"></y>
+<y style="grid-column-end:11; top:36px"></y>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-001.html
new file mode 100644
index 00000000000..b6745f6973b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-001.html
@@ -0,0 +1,127 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Placement involving named lines</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid/#grid-placement-int">
+  <link rel="match" href="masonry-grid-placement-named-lines-001-ref.html">
+  <style>
+body,html { color:black; background:white; font-size:15px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: grid;
+  position: relative;
+  border: 1px solid;
+  grid-template-columns: [A-start] 60px 60px 60px;
+  grid-template-rows: masonry;
+  grid-template-areas: "B A";
+  grid-auto-columns: 40px;
+  grid-gap: 1px;
+}
+
+x {
+  background: grey;
+  border: 1px solid;
+}
+y {
+  position: absolute;
+  border-top: 1px solid blue;
+  height:0;left:0;right:0;
+}
+
+  </style>
+</head>
+<body>
+
+<pre>grid-column-start:</pre>
+<div class="grid" style="padding-right:13px; border-right-width:5px">
+<x style="grid-column:1; background:grey">&nbsp;</x>
+<x style="grid-column-start:-1">-1</x>
+<x style="grid-column-start:4">4</x>
+<x style="grid-column-start:-2">-2</x>
+<x style="grid-column-start:-3">-3</x>
+<x style="grid-column-start:-4">-4</x>
+<x style="grid-column-start:-5">-5</x>
+<x style="grid-column-start:A-start -1">A -1</x>
+<x style="grid-column-start:B -1">B -1</x>
+<x style="grid-column-start:A-start -2">A -2</x>
+<x style="grid-column-start:A-start -3">A -3</x>
+<x style="grid-column-start:A-start -4">A -4</x>
+<x style="grid-column-start:A-start -5">A -5</x>
+<x style="grid-column-start:A-start">A</x>
+<x style="grid-column-start:B">B</x>
+<x style="grid-column-start:A-start 1">A 1</x>
+<x style="grid-column-start:A-start 2">A 2</x>
+<x style="grid-column-start:A-start 3">A 3</x>
+<x style="grid-column-start:A-start 4">A 4</x>
+<x style="grid-column-start:A-start 5">A 5</x>
+<y style="grid-column-start:-1; top:0"></y>
+<y style="grid-column-start:4; top:2px"></y>
+<y style="grid-column-start:-2; top:4px"></y>
+<y style="grid-column-start:-3; top:6px"></y>
+<y style="grid-column-start:-4; top:8px"></y>
+<y style="grid-column-start:-5; top:10px"></y>
+<y style="grid-column-start:A-start -1; top:12px"></y>
+<y style="grid-column-start:B -1; top:14px"></y>
+<y style="grid-column-start:A-start -2; top:16px"></y>
+<y style="grid-column-start:A-start -3; top:18px"></y>
+<y style="grid-column-start:A-start -4; top:20px"></y>
+<y style="grid-column-start:A-start -5; top:22px"></y>
+<y style="grid-column-start:A-start; top:24px"></y>
+<y style="grid-column-start:B; top:26px"></y>
+<y style="grid-column-start:A-start 1; top:28px"></y>
+<y style="grid-column-start:A-start 2; top:30px"></y>
+<y style="grid-column-start:A-start 3; top:32px"></y>
+<y style="grid-column-start:A-start 4; top:34px"></y>
+<y style="grid-column-start:A-start 5; top:36px"></y>
+</div>
+
+<pre>grid-column-end:</pre>
+<div class="grid" style="padding-left:13px;">
+<x style="grid-column:1; background:grey">&nbsp;</x>
+<x style="grid-column-end:-1">-1</x>
+<x style="grid-column-end:4">4</x>
+<x style="grid-column-end:-5">-5</x>
+<x style="grid-column-end:-4">-4</x>
+<x style="grid-column-end:-3">-3</x>
+<x style="grid-column-end:-2">-2</x>
+<x style="grid-column-end:A-start -1">A -1</x>
+<x style="grid-column-end:B -1">B -1</x>
+<x style="grid-column-end:A-start -2">A -2</x>
+<x style="grid-column-end:A-start -3">A -3</x>
+<x style="grid-column-end:A-start -4">A -4</x>
+<x style="grid-column-end:A-start -5">A -5</x>
+<x style="grid-column-end:A-start">A</x>
+<x style="grid-column-end:B">B</x>
+<x style="grid-column-end:A-start 1">A 1</x>
+<x style="grid-column-end:A-start 2">A 2</x>
+<x style="grid-column-end:A-start 3">A 3</x>
+<x style="grid-column-end:A-start 4">A 4</x>
+<x style="grid-column-end:A-start 5">A 5</x>
+<y style="grid-column-end:-1; top:0"></y>
+<y style="grid-column-end:4; top:2px"></y>
+<y style="grid-column-end:-5; top:4px"></y>
+<y style="grid-column-end:-4; top:6px"></y>
+<y style="grid-column-end:-3; top:8px"></y>
+<y style="grid-column-end:-2; top:10px"></y>
+<y style="grid-column-end:A-start -1; top:12px"></y>
+<y style="grid-column-end:B -1; top:14px"></y>
+<y style="grid-column-end:A-start -2; top:16px"></y>
+<y style="grid-column-end:A-start -3; top:18px"></y>
+<y style="grid-column-end:A-start -4; top:20px"></y>
+<y style="grid-column-end:A-start -5; top:22px"></y>
+<y style="grid-column-end:A-start; top:24px"></y>
+<y style="grid-column-end:B; top:26px"></y>
+<y style="grid-column-end:A-start 1; top:28px"></y>
+<y style="grid-column-end:A-start 2; top:30px"></y>
+<y style="grid-column-end:A-start 3; top:32px"></y>
+<y style="grid-column-end:A-start 4; top:34px"></y>
+<y style="grid-column-end:A-start 5; top:36px"></y>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-002-ref.html
new file mode 100644
index 00000000000..dd589f90c5f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-002-ref.html
@@ -0,0 +1,80 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Placement involving named lines</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+body,html { color:black; background:white; font:15px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: grid;
+  grid-template-columns: 40px 40px 40px 60px 60px 60px 40px 40px 40px 40px 40px 40px 40px;
+  position: relative;
+  border: 1px solid;
+  grid-auto-flow: dense;
+  column-gap: 1px;
+}
+
+x {
+  background: grey;
+}
+y {
+  position: absolute;
+  border: 1px solid blue;
+  top:0;height:0;left:0;right:0;
+  grid-row-end:span 1!important;
+}
+
+  </style>
+</head>
+<body>
+
+<pre>grid-column: / span A-start 2</pre>
+<div class="grid">
+<x style="grid-row:1;  grid-column:4">&nbsp;</x>
+<x style="grid-row:1;  grid-column:7/span 2;">-1</x>
+<x style="grid-row:2;  grid-column:7/span 2;">4</x>
+<x style="grid-row:4;  grid-column:6/span 3;">-2</x>
+<x style="grid-row:5;  grid-column:5/span 4;">-3</x>
+<x style="grid-row:6;  grid-column:4/span 4;">-4</x>
+<x style="grid-row:7;  grid-column:3/span 2;">-5</x>
+<x style="grid-row:7;  grid-column:5/span 4;">A -1</x>
+<x style="grid-row:9;  grid-column:3/span 2;">B -1</x>
+<x style="grid-row:10; grid-column:4/span 4;">A -2</x>
+<x style="grid-row:11; grid-column:3/span 2;">A -3</x>
+<x style="grid-row:12; grid-column:2/span 3;">A -4</x>
+<x style="grid-row:13; grid-column:1/span 4;">A -5</x>
+<x style="grid-row:14; grid-column:4/span 4;">A</x>
+<x style="grid-row:15; grid-column:4/span 4;">B</x>
+<x style="grid-row:16; grid-column:4/span 4;">A 1</x>
+<x style="grid-row:17; grid-column:5/span 4;">A 2</x>
+<x style="grid-row:18; grid-column:8/span 2;">A 3</x>
+<x style="grid-row:1;  grid-column:9/span 2;">A 4</x>
+<x style="grid-row:2;  grid-column:10/span 2;">A 5</x>
+<y style="grid-row:1;  grid-column:7/span 2;"></y>
+<y style="grid-row:2;  grid-column:7/span 2;"></y>
+<y style="grid-row:4;  grid-column:6/span 3;"></y>
+<y style="grid-row:5;  grid-column:5/span 4;"></y>
+<y style="grid-row:6;  grid-column:4/span 4;"></y>
+<y style="grid-row:7;  grid-column:3/span 2;"></y>
+<y style="grid-row:7;  grid-column:5/span 4;"></y>
+<y style="grid-row:9;  grid-column:3/span 2;"></y>
+<y style="grid-row:10; grid-column:4/span 4;"></y>
+<y style="grid-row:11; grid-column:3/span 2;"></y>
+<y style="grid-row:12; grid-column:2/span 3;"></y>
+<y style="grid-row:13; grid-column:1/span 4;"></y>
+<y style="grid-row:14; grid-column:4/span 4;"></y>
+<y style="grid-row:15; grid-column:4/span 4;"></y>
+<y style="grid-row:16; grid-column:4/span 4;"></y>
+<y style="grid-row:17; grid-column:5/span 4;"></y>
+<y style="grid-row:18; grid-column:8/span 2;"></y>
+<y style="grid-row:1;  grid-column:9/span 2;"></y>
+<y style="grid-row:2;  grid-column:10/span 2;"></y>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-002.html
new file mode 100644
index 00000000000..0ad0dfcea37
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-placement-named-lines-002.html
@@ -0,0 +1,85 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Placement involving named lines</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid/#grid-placement-int">
+  <link rel="match" href="masonry-grid-placement-named-lines-002-ref.html">
+  <style>
+body,html { color:black; background:white; font:15px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: grid;
+  position: relative;
+  border: 1px solid;
+  grid-template-columns: [A-start] 60px 60px 60px;
+  grid-template-rows: masonry;
+  grid-template-areas: "B A";
+  grid-auto-columns: 40px;
+  grid-auto-flow: dense;
+  gap: 0 1px;
+}
+
+x {
+  background: grey;
+}
+y {
+  position: absolute;
+  border: 1px solid blue;
+  bottom:0;height:0;left:0;right:0;
+  grid-row-end:span 1!important;
+}
+
+  </style>
+</head>
+<body>
+
+<pre>grid-column: / span A-start 2</pre>
+<div class="grid">
+<x style="grid-column:1">&nbsp;</x>
+<x style="grid-column:-1/span A-start 2">-1</x>
+<x style="grid-column:4/span A-start 2">4</x>
+<x style="grid-column:-2/span A-start 2">-2</x>
+<x style="grid-column:-3/span A-start 2">-3</x>
+<x style="grid-column:-4/span A-start 2">-4</x>
+<x style="grid-column:-5/span A-start 2">-5</x>
+<x style="grid-column:A-start -1/span A-start 2">A -1</x>
+<x style="grid-column:B -1/span A-start 2">B -1</x>
+<x style="grid-column:A-start -2/span A-start 2">A -2</x>
+<x style="grid-column:A-start -3/span A-start 2">A -3</x>
+<x style="grid-column:A-start -4/span A-start 2">A -4</x>
+<x style="grid-column:A-start -5/span A-start 2">A -5</x>
+<x style="grid-column:A-start/span A-start 2">A</x>
+<x style="grid-column:B/span B">B</x>
+<x style="grid-column:A-start 1/span A-start 2">A 1</x>
+<x style="grid-column:A-start 2/span A-start 2">A 2</x>
+<x style="grid-column:A-start 3/span A-start 2">A 3</x>
+<x style="grid-column:A-start 4/span A-start 2">A 4</x>
+<x style="grid-column:A-start 5/span A-start 2">A 5</x>
+<y style="grid-column:-1/span A-start 2; top:0em"></y>
+<y style="grid-column:4/span A-start 2; top:1em"></y>
+<y style="grid-column:-2/span A-start 2; top:2em"></y>
+<y style="grid-column:-3/span A-start 2; top:3em"></y>
+<y style="grid-column:-4/span A-start 2; top:4em"></y>
+<y style="grid-column:-5/span A-start 2; top:5em"></y>
+<y style="grid-column:A-start -1/span A-start 2; top:5em"></y>
+<y style="grid-column:B -1/span A-start 2; top:6em"></y>
+<y style="grid-column:A-start -2/span A-start 2; top:7em"></y>
+<y style="grid-column:A-start -3/span A-start 2; top:8em"></y>
+<y style="grid-column:A-start -4/span A-start 2; top:9em"></y>
+<y style="grid-column:A-start -5/span A-start 2; top:10em"></y>
+<y style="grid-column:A-start/span A-start 2; top:11em"></y>
+<y style="grid-column:B/span B; top:12em"></y>
+<y style="grid-column:A-start 1/span A-start 2; top:13em"></y>
+<y style="grid-column:A-start 2/span A-start 2; top:14em"></y>
+<y style="grid-column:A-start 3/span A-start 2; top:15em"></y>
+<y style="grid-column:A-start 4/span A-start 2; top:0em"></y>
+<y style="grid-column:A-start 5/span A-start 2; top:1em"></y>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-template-columns-computed-withcontent.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-template-columns-computed-withcontent.html
new file mode 100644
index 00000000000..f2a47d9809a
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-grid-template-columns-computed-withcontent.html
@@ -0,0 +1,95 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<title>CSS Masonry Test: getComputedStyle().gridTemplateColumns</title>
+<link rel="help" href="https://drafts.csswg.org/css-grid-1/#propdef-grid-template-columns">
+<meta name="assert" content="grid-template-columns computed value is the keyword none or a computed track list.">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/css/support/computed-testcommon.js"></script>
+<style>
+  #target {
+    display: grid;
+    grid-template-rows: masonry;
+    font-size: 40px;
+    min-width: 200px;
+    width: 300px;
+    max-width: 400px;
+    min-height: 500px;
+    height: 600px;
+    max-height: 700px;
+  }
+  #child {
+    min-width: 20px;
+    width: 30px;
+    max-width: 40px;
+    min-height: 50px;
+    height: 60px;
+    max-height: 70px;
+  }
+</style>
+</head>
+<body>
+<div id="container">
+  <div id="target">
+    <div id="child"></div>
+  </div>
+</div>
+<script>
+test_computed_value("grid-template-rows", 'masonry', 'masonry');
+test_computed_value("grid-template-columns", 'none', 'none'); // "none" without #child
+
+// track-size <fixed-breadth> = <length-percentage> | <flex> | min-content | max-content | auto
+test_computed_value("grid-template-columns", '20%', '60px'); // 20% * width
+test_computed_value("grid-template-columns", 'calc(-0.5em + 10px)', '0px');
+test_computed_value("grid-template-columns", 'calc(0.5em + 10px)', '30px');
+test_computed_value("grid-template-columns", 'calc(30% + 40px)', '130px'); // 30% * width + 40px
+test_computed_value("grid-template-columns", '5fr', '300px'); // width
+test_computed_value("grid-template-columns", 'min-content', '30px');
+test_computed_value("grid-template-columns", 'max-content', '30px');
+test_computed_value("grid-template-columns", 'auto', '300px'); // width
+
+// track-size minmax( <inflexible-breadth> , <track-breadth> )
+test_computed_value("grid-template-columns", 'minmax(10px, auto)', '300px'); // width
+test_computed_value("grid-template-columns", 'minmax(20%, max-content)', '60px'); // 20% * width
+test_computed_value("grid-template-columns", 'minmax(min-content, calc(-0.5em + 10px))', '30px');
+test_computed_value("grid-template-columns", 'minmax(auto, 0)', '30px');
+
+// track-size fit-content( <length-percentage> )
+test_computed_value("grid-template-columns", 'fit-content(70px)', '30px');
+test_computed_value("grid-template-columns", 'fit-content(20%)', '30px');
+test_computed_value("grid-template-columns", 'fit-content(calc(-0.5em + 10px))', '30px');
+
+// <track-repeat> = repeat( [ <positive-integer> ] , [ <line-names>? <track-size> ]+ <line-names>? )
+test_computed_value("grid-template-columns", 'repeat(1, 10px)', '10px');
+test_computed_value("grid-template-columns", 'repeat(1, [one two] 20%)', '[one two] 60px');
+test_computed_value("grid-template-columns", 'repeat(2, minmax(10px, auto))', '160px 140px');
+
+test_computed_value("grid-template-columns", 'repeat(2, fit-content(20%) [three four] 30px 40px [five six])',
+                    '30px [three four] 30px 40px [five six] 0px [three four] 30px 40px [five six]');
+
+// <track-list> = [ <line-names>? [ <track-size> | <track-repeat> ] ]+ <line-names>?
+test_computed_value("grid-template-columns", 'min-content repeat(5, minmax(10px, auto))',
+                    '30px 54px 54px 54px 54px 54px');
+test_computed_value("grid-template-columns", '[] 150px [] 1fr []', '150px 150px');
+
+// <auto-repeat> = repeat( [ auto-fill | auto-fit ] , [ <line-names>? <fixed-size> ]+ <line-names>? )
+test_computed_value("grid-template-columns", 'repeat(auto-fill, 200px)', '200px');
+test_computed_value("grid-template-columns", 'repeat(auto-fit, [one] 20%)',
+                    '[one] 60px [one] 0px [one] 0px [one] 0px [one] 0px');
+test_computed_value("grid-template-columns", 'repeat(auto-fill, minmax(100px, 5fr) [two])',
+                    '100px [two] 100px [two] 100px [two]');
+test_computed_value("grid-template-columns", 'repeat(auto-fit, [three] minmax(max-content, 6em) [four])',
+                    '[three] 240px [four]');
+
+// <auto-track-list> =
+// [ <line-names>? [ <fixed-size> | <fixed-repeat> ] ]* <line-names>?
+// <auto-repeat>
+// [ <line-names>? [ <fixed-size> | <fixed-repeat> ] ]* <line-names>?
+
+test_computed_value("grid-template-columns", '[one] repeat(2, minmax(50px, auto)) [two] 30px [three] repeat(auto-fill, 10px) 40px [four five] repeat(2, minmax(200px, auto)) [six]',
+                    '[one] 50px 50px [two] 30px [three] 10px 40px [four five] 200px 200px [six]');
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-001-ref.html
new file mode 100644
index 00000000000..898bff16d8e
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-001-ref.html
@@ -0,0 +1,271 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout intrinsic sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,auto);
+  grid-auto-rows: 1em;
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+}
+.fr {
+  grid-template-columns: 1fr 2fr 1fr 1fr;
+}
+.mixed {
+  grid-template-columns: 1fr 2fr min-content max-content;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid style="grid-template-columns: 1ch repeat(3,auto)">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid style="grid-template-columns: repeat(4,1ch)">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+<!-- ditto with 'fr' sizing -->
+
+<grid class="fr">
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid class="fr" style="grid-template-columns: 1ch 2fr 1fr 1fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid class="fr" style="grid-template-columns: 1ch 2ch 1ch 1ch">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+
+<!-- ditto with mixed sizing -->
+
+<grid class="mixed" style="grid-template-columns: 2ch 4ch 1ch 1ch">
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid class="mixed" style="grid-template-columns: 1ch 2ch 1ch 1ch">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid class="mixed" style="grid-template-columns: 1ch 2ch 1ch 1ch">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-001.html
new file mode 100644
index 00000000000..0f6cdb14954
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-001.html
@@ -0,0 +1,273 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout intrinsic sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-intrinsic-sizing-001-ref.html">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,auto);
+  grid-template-rows: masonry;
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+}
+.fr {
+  grid-template-columns: 1fr 2fr 1fr 1fr;
+}
+.mixed {
+  grid-template-columns: 1fr 2fr min-content max-content;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+<!-- ditto with 'fr' sizing -->
+
+<grid class="fr">
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+
+<!-- ditto with mixed sizing -->
+
+<grid class="mixed">
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-002-ref.html
new file mode 100644
index 00000000000..4f6519db949
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-002-ref.html
@@ -0,0 +1,272 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout intrinsic sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,auto);
+  grid-auto-rows: 1em;
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+  width: min-content;
+}
+.fr {
+  grid-template-columns: 1fr 2fr 1fr 1fr;
+}
+.mixed {
+  grid-template-columns: 1fr 2fr min-content max-content;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid style="grid-template-columns: 1ch repeat(3,auto)">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid style="grid-template-columns: repeat(4,1ch)">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+<!-- ditto with 'fr' sizing -->
+
+<grid class="fr">
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid class="fr" style="grid-template-columns: 1ch 2fr 1fr 1fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid class="fr" style="grid-template-columns: 1ch 1ch 1ch 1ch">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+
+<!-- ditto with mixed sizing -->
+
+<grid class="mixed" style="grid-template-columns: 2ch 1ch 1ch 1ch">
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid class="mixed" style="grid-template-columns: 1ch 1ch 1ch 1ch">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid class="mixed" style="grid-template-columns: 1ch 1ch 1ch 1ch">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-002.html
new file mode 100644
index 00000000000..db83299bf50
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-002.html
@@ -0,0 +1,274 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout intrinsic sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-intrinsic-sizing-002-ref.html">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,auto);
+  grid-template-rows: masonry;
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+  width: min-content;
+}
+.fr {
+  grid-template-columns: 1fr 2fr 1fr 1fr;
+}
+.mixed {
+  grid-template-columns: 1fr 2fr min-content max-content;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+<!-- ditto with 'fr' sizing -->
+
+<grid class="fr">
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+
+<!-- ditto with mixed sizing -->
+
+<grid class="mixed">
+  <item style="width:2ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-003-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-003-ref.html
new file mode 100644
index 00000000000..61eb21570df
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-003-ref.html
@@ -0,0 +1,269 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout min-content sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,auto);
+  grid-auto-rows: 1em;
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+  width: min-content;
+}
+.fr {
+  grid-template-columns: 1fr 2fr 1fr 1fr;
+}
+.mixed {
+  grid-template-columns: 1fr 2fr min-content max-content;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+item.start { align-self: start; }
+</style>
+</head>
+<body>
+
+<grid style="grid-template-rows: 1em 2em">
+  <item style="width:2ch">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid style="grid: 1em 2em / 1ch repeat(3,auto); ">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid style="grid-template-rows: 2em 2em">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid style="grid-template-rows: 2em 1em">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid style="grid-template-rows: 2em 1em">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid style="grid-template-rows: 2em 1em">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid style="grid-template-rows: 2em 1em">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid style="grid-template-rows: 2em 1em">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid style="grid: 2em 1em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+<!-- ditto with 'fr' sizing -->
+
+<grid class="fr" style="grid: 1em 2em / 2ch 2fr 1fr 1fr">
+  <item style="width:2ch" class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item>5 5</item>
+</grid>
+
+<grid class="fr" style="grid: 1em 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid class="fr" style="grid: 2em 2em / 1ch 2ch repeat(2,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid class="fr" style="grid: 2em 1em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid class="fr" style="grid: 2em 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr" style="grid: 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr" style="grid: 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="fr" style="grid: 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="fr" style="grid: 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+<!-- ditto with mixed sizing -->
+
+<grid class="mixed" style="grid: 1em 2em / 2ch repeat(3,1ch)">
+  <item style="width:2ch" class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item>5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 1em 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em 2em / 1ch 2ch repeat(2,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em 1em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em / repeat(4,1ch)">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-003.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-003.html
new file mode 100644
index 00000000000..e43bc86c9b9
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-003.html
@@ -0,0 +1,270 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout min-content sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-intrinsic-sizing-003-ref.html">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,auto);
+  grid-template-rows: masonry;
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+  width: min-content;
+}
+.fr {
+  grid-template-columns: 1fr 2fr 1fr 1fr;
+}
+.mixed {
+  grid-template-columns: 1fr 2fr min-content max-content;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="width:2ch">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+<!-- ditto with 'fr' sizing -->
+
+<grid class="fr">
+  <item style="width:2ch">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+<!-- ditto with mixed sizing -->
+
+<grid class="mixed">
+  <item style="width:2ch">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-004-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-004-ref.html
new file mode 100644
index 00000000000..6a5d81fedb2
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-004-ref.html
@@ -0,0 +1,270 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout max-content sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: 1ch 3ch 3ch 1ch;
+  grid-auto-rows: 1em;
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+  align-items: start;
+  width: max-content;
+}
+.fr {
+  grid-template-columns: 1fr 2fr 1fr 1fr;
+}
+.mixed {
+  grid-template-columns: 1fr 2fr min-content max-content;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+item.start { align-self: start; }
+</style>
+</head>
+<body>
+
+<grid style="grid: 1em 2em / 2ch 3ch 3ch 1ch">
+  <item style="width:2ch">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid style="grid: 1em 2em / 1ch 3ch 3ch 1ch; ">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid style="grid-template-rows: 1em 2em">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid>
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid>
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid>
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid>
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+<!-- ditto with 'fr' sizing -->
+
+<grid class="fr">
+  <item style="width:2ch" class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item>5 5</item>
+</grid>
+
+<grid class="fr" style="grid: 1em 2em / 3ch 6ch 3ch 3ch">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid class="fr" style="grid: 1em 2em / 3ch 6ch 3ch 3ch">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+<!-- ditto with mixed sizing -->
+
+<grid class="mixed" style="grid: 1em 2em / 2ch 4ch 1ch 1ch">
+  <item style="width:2ch" class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item>5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 1em 2em / calc(3ch/2) 3ch 1ch 1ch">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 1em 2em / calc(3ch/2) 3ch 1ch 1ch">
+  <item class="start">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item class="start">4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em 1em / calc(3ch/2) 3ch 1ch 1ch">
+  <item class="start">1</item>
+  <item class="start">2 2</item>
+  <item class="start">3 3</item>
+  <item class="start">4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em 1em 1em / calc(3ch/2) 3ch 1ch 1ch">
+  <item class="start">1</item>
+  <item class="start">2 2</item>
+  <item class="start">3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em 1em / calc(3ch/2) 3ch 1ch 1ch">
+  <item class="start">1</item>
+  <item class="start">2 2</item>
+  <item class="start">3 3</item>
+  <item class="start">4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em 1em / calc(3ch/2) 3ch 1ch 1ch">
+  <item class="start">1</item>
+  <item class="start">2 2</item>
+  <item class="start">3 3</item>
+  <item class="start">4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em 1em / calc(3ch/2) 3ch 1ch 1ch">
+  <item class="start">1</item>
+  <item class="start">2 2</item>
+  <item class="start">3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="mixed" style="grid: 2em 1em / calc(3ch/2) 3ch 1ch 1ch">
+  <item class="start">1</item>
+  <item class="start">2 2</item>
+  <item class="start">3 3</item>
+  <item class="start">4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-004.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-004.html
new file mode 100644
index 00000000000..5365208c00f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-004.html
@@ -0,0 +1,270 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout max-content sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-intrinsic-sizing-004-ref.html">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,auto);
+  grid-template-rows: masonry;
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+  width: max-content;
+}
+.fr {
+  grid-template-columns: 1fr 2fr 1fr 1fr;
+}
+.mixed {
+  grid-template-columns: 1fr 2fr min-content max-content;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="width:2ch">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+<!-- ditto with 'fr' sizing -->
+
+<grid class="fr">
+  <item style="width:2ch">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="fr">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+<!-- ditto with mixed sizing -->
+
+<grid class="mixed">
+  <item style="width:2ch">1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:2ch; grid-column:2">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:4ch; grid-column:2/span 2">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:3ch; grid-column:2/span 2">5 5</item>
+  <item style="width:5ch; grid-column:1/span 3">6</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 4">5 5</item>
+</grid>
+
+<grid class="mixed">
+  <item>1</item>
+  <item>2 2</item>
+  <item>3 3</item>
+  <item>4</item>
+  <item style="width:6ch; grid-column:span 3">5 5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-005-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-005-ref.html
new file mode 100644
index 00000000000..e564fb1b3e6
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-005-ref.html
@@ -0,0 +1,83 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout intrinsic sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-auto-flow: column;
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+  writing-mode: vertical-lr;
+}
+</style>
+</head>
+<body>
+
+<grid style="grid-template-rows: 3ch repeat(3,1ch)">
+  <item style="height:3ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5 5</item>
+  <item>6</item>
+  <item>7</item>
+  <item>8</item>
+  <item>9 9</item>
+</grid>
+
+<grid style="grid-template-rows: repeat(4,1ch)">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="height:3ch">5 5</item>
+  <item>6</item>
+  <item>7</item>
+  <item>8</item>
+  <item>9 9</item>
+</grid>
+
+<grid style="grid-template-rows: 3ch repeat(3,1ch)">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="height:3ch; grid-row:1">5 5</item>
+  <item>6</item>
+  <item>7</item>
+  <item>8</item>
+  <item>9 9</item>
+</grid>
+
+<grid style="grid-template-rows: 3ch repeat(3,1ch)">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="height:3ch; grid-column:1">5 5</item>
+  <item>6</item>
+  <item>7</item>
+  <item>8</item>
+  <item>9 9</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-005.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-005.html
new file mode 100644
index 00000000000..cf9b680869f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-005.html
@@ -0,0 +1,86 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout intrinsic sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-intrinsic-sizing-005-ref.html">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: masonry;
+  grid-template-rows: repeat(4,auto);
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+  writing-mode: vertical-lr;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="height:3ch">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5 5</item>
+  <item>6</item>
+  <item>7</item>
+  <item>8</item>
+  <item>9 9</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="height:3ch">5 5</item>
+  <item>6</item>
+  <item>7</item>
+  <item>8</item>
+  <item>9 9</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="height:3ch; grid-row:1">5 5</item>
+  <item>6</item>
+  <item>7</item>
+  <item>8</item>
+  <item>9 9</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="height:3ch; grid-column:1">5 5</item>
+  <item>6</item>
+  <item>7</item>
+  <item>8</item>
+  <item>9 9</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-006-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-006-ref.html
new file mode 100644
index 00000000000..e1cb015cfe8
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-006-ref.html
@@ -0,0 +1,60 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout intrinsic sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-auto-flow: column;
+  grid-template-columns: 1ch;
+  grid-template-rows: repeat(4,1em);
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="width:3ch">1 1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-row:2">5 5</item>
+</grid>
+
+<grid>
+  <item style="width:3ch">1 1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-row:2">5 5</item>
+</grid>
+
+<grid style="height:5em">
+  <item style="width:3ch">1 1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item style="grid-row:2">5 5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-006.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-006.html
new file mode 100644
index 00000000000..49fd53bb79b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-intrinsic-sizing-006.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout intrinsic sizing</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-intrinsic-sizing-006-ref.html">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 Ahem; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: masonry;
+  grid-template-rows: repeat(4,auto);
+  border: 1px solid;
+  padding: 0 1px 0 2px;
+  vertical-align: top;
+}
+
+item {
+  background-color: #444;
+  color: blue;
+}
+</style>
+</head>
+<body>
+
+<grid style="max-height:5em; grid-template-rows: repeat(auto-fill,1em);">
+  <item>1 1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid style="min-height:4em; grid-template-rows: repeat(auto-fill,1em);">
+  <item>1 1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+<grid style="height:5em; grid-template-rows: repeat(auto-fill,1em);">
+  <item>1 1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5 5</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-001-ref.html
new file mode 100644
index 00000000000..7108a11a100
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-001-ref.html
@@ -0,0 +1,46 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout using `grid-column/row`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-template-columns: repeat(4,80px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="margin-top:10px">3</item>
+  <item style="grid-column:span 2">1</item>
+  <item>2</item>
+  <item style="grid-column:2">5</item>
+  <item style="grid-column:span 2">4</item>
+  <item style="grid-column:1">6</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-001.html
new file mode 100644
index 00000000000..2f8cfbfacc2
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-001.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout using `grid-column/row`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-item-placement-001-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-template-columns: repeat(4,80px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item style="margin-top:10px">3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-002-ref.html
new file mode 100644
index 00000000000..a02009ec308
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-002-ref.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout using `grid-column/row`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-template-columns: repeat(4,80px);
+  grid-template-rows: auto;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="grid-column:1/-1">1</item>
+  <item>3</item>
+  <x></x>
+  <item>2</item>
+  <item>5</item>
+  <item style="grid-column:1/-2">4</item>
+  <item>6</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-002.html
new file mode 100644
index 00000000000..5f7083b1733
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-002.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout using `grid-column/row`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-item-placement-002-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-auto-columns: 80px;
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="grid-column:foo 2; grid-row:span 2">2</item>
+  <item>3</item>
+  <item style="grid-column:span 3">4</item>
+  <item>5</item>
+  <item>6</item>
+  <item style="grid-column:span 4; grid-row:-100">1</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-003-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-003-ref.html
new file mode 100644
index 00000000000..5cbd8db9ef9
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-003-ref.html
@@ -0,0 +1,46 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout using `grid-column/row` and `dense`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-auto-columns: 80px;
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item>1</item>
+  <item>3</item>
+  <item>2</item>
+  <item style="grid-column:span 3">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-003.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-003.html
new file mode 100644
index 00000000000..4d490c18d5d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-003.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout using `grid-column/row` and `dense`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-item-placement-003-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-auto-flow: dense;
+  grid-auto-columns: 80px;
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="grid-row:-100">1</item>
+  <item style="grid-column:foo 2; grid-row:span 2">2</item>
+  <item style="grid-column:span 3">4</item>
+  <item>3</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-004-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-004-ref.html
new file mode 100644
index 00000000000..75d6b741c2f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-004-ref.html
@@ -0,0 +1,107 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout using `grid-column/row`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: auto;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:2/1">5</item>
+  <item style="grid-column:2/3">6</item>
+  <item style="grid-column:3/span 2">4</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:2/1">5</item>
+  <item style="grid-column:2/3">6</item>
+  <item style="grid-column:3/span 2">4</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:2/1">5</item>
+  <item style="grid-column:2/3">6</item>
+  <item style="grid-column:3/span 2">4</item>
+</grid>
+
+<div style="direction:rtl">
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:2/1">5</item>
+  <item style="grid-column:2/3">6</item>
+  <item style="grid-column:3/span 2">4</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:2/1">5</item>
+  <item style="grid-column:2/3">6</item>
+  <item style="grid-column:3/span 2">4</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:2/1">5</item>
+  <item style="grid-column:2/3">6</item>
+  <item style="grid-column:3/span 2">4</item>
+</grid>
+</div>
+
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-004.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-004.html
new file mode 100644
index 00000000000..4d1a454a865
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-004.html
@@ -0,0 +1,109 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout using `grid-column/row`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-item-placement-004-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: next">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: ordered">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: next ordered">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<div style="direction:rtl">
+<grid>
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: next">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: ordered">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: next ordered">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+</div>
+
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-005-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-005-ref.html
new file mode 100644
index 00000000000..806f314300d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-005-ref.html
@@ -0,0 +1,107 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout using `grid-column/row`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: auto;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:1/2">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">5</item>
+  <item style="grid-column:4/5">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">5</item>
+  <item style="grid-column:4/5">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:1/2">6</item>
+</grid>
+
+<div style="direction:rtl">
+<grid>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:1/2">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">5</item>
+  <item style="grid-column:4/5">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">3</item>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">5</item>
+  <item style="grid-column:4/5">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:2/span 2">1</item>
+  <item style="grid-column:4/5">2</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:1/2">6</item>
+</grid>
+</div>
+
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-005.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-005.html
new file mode 100644
index 00000000000..ddfbc9e54e4
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-005.html
@@ -0,0 +1,109 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout using `grid-column/row`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-item-placement-005-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: ordered">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: ordered next">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: next">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<div style="direction:rtl">
+<grid>
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: ordered">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: ordered next">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="masonry-auto-flow: next">
+  <item style="grid-column:2/span 2">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+</div>
+
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-006-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-006-ref.html
new file mode 100644
index 00000000000..a6e9b75d0e6
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-006-ref.html
@@ -0,0 +1,144 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry item placement</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="padding-top:30px; grid-column:1/2">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid>
+  <item style="padding-top:30px; grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:1/2">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 3">4</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:4/5">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 4">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+
+<span class="next">
+<grid>
+  <item style="padding-top:30px; grid-column:1/2">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+
+<grid>
+  <item style="padding-top:30px; grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">5</item>
+  <item style="grid-column:4/5">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 3">4</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:1/2">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 4">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+</span>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-006.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-006.html
new file mode 100644
index 00000000000..0082d72df26
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-006.html
@@ -0,0 +1,149 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry item placement</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-item-placement-006-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+.next > grid {
+  masonry-auto-flow: next;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item style="padding-top:30px">1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 3">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 4">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<span class="next">
+<grid>
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item style="padding-top:30px">1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 3">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 4">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+</span>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-007-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-007-ref.html
new file mode 100644
index 00000000000..50236046fb0
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-007-ref.html
@@ -0,0 +1,145 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry item placement (RTL)</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  direction: rtl;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="padding-top:30px; grid-column:1/2">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid>
+  <item style="padding-top:30px; grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:3/span 2">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:1/2">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 3">4</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:4/5">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 4">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+
+<span class="next">
+<grid>
+  <item style="padding-top:30px; grid-column:1/2">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+
+<grid>
+  <item style="padding-top:30px; grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 2">4</item>
+  <item style="grid-column:3/4">5</item>
+  <item style="grid-column:4/5">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 3">4</item>
+  <item style="grid-column:4/5">5</item>
+  <item style="grid-column:1/2">6</item>
+</grid>
+
+<grid>
+  <item style="grid-column:1/2">1</item>
+  <item style="padding-top:30px; grid-column:2/3">2</item>
+  <item style="padding-top:10px; grid-column:3/4">3</item>
+  <item style="grid-column:1/span 4">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:2/3">6</item>
+</grid>
+</span>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-007.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-007.html
new file mode 100644
index 00000000000..67a02560f45
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-item-placement-007.html
@@ -0,0 +1,150 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry item placement (RTL)</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-item-placement-007-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  direction: rtl;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+.next > grid {
+  masonry-auto-flow: next;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item style="padding-top:30px">1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 3">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 4">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<span class="next">
+<grid>
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item style="padding-top:30px">1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 2">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 3">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item style="padding-top:10px">3</item>
+  <item style="grid-column:span 4">4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+</span>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-001-ref.html
new file mode 100644
index 00000000000..f7d9ccf48f1
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-001-ref.html
@@ -0,0 +1,125 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `justify-content` in grid axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: 1em auto;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  width: 100px;
+  align-items: start;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { padding-top:30px; grid-row:span 2; }
+</style>
+</head>
+<body>
+
+<grid style="justify-content:start">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:stretch">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:space-between">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:space-around">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:space-evenly">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-001.html
new file mode 100644
index 00000000000..3d60ac19feb
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-001.html
@@ -0,0 +1,125 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `justify-content` in grid axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-justify-content-001-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  width: 100px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+</style>
+</head>
+<body>
+
+<grid style="justify-content:start">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item>1</item>
+  <item style="padding-top:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:stretch">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-between">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-around">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-evenly">
+  <item style="padding-top:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-002-ref.html
new file mode 100644
index 00000000000..6889af7eacc
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-002-ref.html
@@ -0,0 +1,126 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `justify-content` in grid axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: 1em auto;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  height: 100px;
+  writing-mode: vertical-lr;
+  align-items: start;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { padding-right:30px; grid-row:span 2; }
+</style>
+</head>
+<body>
+
+<grid style="justify-content:start">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item style="grid-column:1/2">1</item>
+  <item style="grid-column:2/3" class="tall">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:1/2">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:stretch">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:space-between">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:space-around">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
+
+<grid style="justify-content:space-evenly">
+  <item style="grid-column:1/2" class="tall">1</item>
+  <item style="grid-column:2/3">2</item>
+  <item style="grid-column:3/4">3</item>
+  <item style="grid-column:4/5">4</item>
+  <item style="grid-column:2/3">5</item>
+  <item style="grid-column:3/4">6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-002.html
new file mode 100644
index 00000000000..b1db084d4e7
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-002.html
@@ -0,0 +1,126 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `justify-content` in grid axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-justify-content-002-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: repeat(4,20px);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+  height: 100px;
+  writing-mode: vertical-lr;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+</style>
+</head>
+<body>
+
+<grid style="justify-content:start">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item>1</item>
+  <item style="padding-right:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item>1</item>
+  <item style="padding-right:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item>1</item>
+  <item style="padding-right:30px">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:stretch">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-between">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-around">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-evenly">
+  <item style="padding-right:30px">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-003-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-003-ref.html
new file mode 100644
index 00000000000..81d0fba4107
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-003-ref.html
@@ -0,0 +1,125 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `justify-content` in masonry axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: 1ch auto;
+  grid-template-rows: repeat(4,20px);
+  background: content-box silver;
+  border: 1px solid;
+  padding: 2px;
+  width: 100px;
+  justify-items: start;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { grid-column:span 2; padding-left: 30px; }
+</style>
+</head>
+<body>
+
+<grid style="justify-content:start">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:stretch">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-003.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-003.html
new file mode 100644
index 00000000000..772984b9e0d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-003.html
@@ -0,0 +1,126 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `justify-content` in masonry axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-justify-content-003-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: masonry;
+  grid-template-rows: repeat(4,20px);
+  background: content-box silver;
+  border: 1px solid;
+  padding: 2px;
+  width: 100px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { padding-left: 30px; }
+</style>
+</head>
+<body>
+
+<grid style="justify-content:start">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:stretch">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-between">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-around">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-evenly">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-004-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-004-ref.html
new file mode 100644
index 00000000000..43af71fc01f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-004-ref.html
@@ -0,0 +1,128 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `justify-content` in masonry axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: 1ch auto;
+  grid-template-rows: repeat(4,20px);
+  background: content-box silver;
+  border: 1px solid;
+  padding: 0 3px 2px 0;
+  width: 100px;
+  height: 120px;
+  align-content: center;
+  justify-items: start;
+  writing-mode: vertical-rl;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { grid-column: span 2; padding: 11px 3px 13px 7px; }
+</style>
+</head>
+<body>
+
+<grid style="justify-content:start">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item style="grid-row:1/2">1</item>
+  <item class="tall" style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:1/2">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:stretch">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item class="tall" style="grid-row:1/2">1</item>
+  <item style="grid-row:2/3">2</item>
+  <item style="grid-row:3/4">3</item>
+  <item style="grid-row:4/5">4</item>
+  <item style="grid-row:2/3">5</item>
+  <item style="grid-row:3/4">6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-004.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-004.html
new file mode 100644
index 00000000000..7d04ffeb4b2
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-content-004.html
@@ -0,0 +1,129 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `justify-content` in masonry axis</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-justify-content-004-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: masonry;
+  grid-template-rows: repeat(4,20px);
+  background: content-box silver;
+  border: 1px solid;
+  padding: 0 3px 2px 0;
+  width: 100px;
+  height: 120px;
+  align-content: center;
+  writing-mode: vertical-rl;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+}
+
+.tall { padding: 11px 3px 13px 7px; }
+</style>
+</head>
+<body>
+
+<grid style="justify-content:start">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:start">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:end">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:center">
+  <item>1</item>
+  <item class="tall">2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:stretch">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-between">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-around">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
+
+<grid style="justify-content:space-evenly">
+  <item class="tall">1</item>
+  <item>2</item>
+  <item>3</item>
+  <item>4</item>
+  <item>5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-001-ref.html
new file mode 100644
index 00000000000..912c9c9f823
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-001-ref.html
@@ -0,0 +1,114 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `justify-tracks` alignment</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; direction:ltr; }
+.swr { writing-mode: sideways-lr; direction:rtl; }
+
+grid {
+  display: inline-flex;
+  flex-flow: row wrap;
+  background: content-box silver;
+  color: #444;
+  padding: 1px 2px;
+  inline-size: 30px;
+  vertical-align: top;
+}
+grid.vll, grid.vrr, grid.vlr, grid.vrl, grid.swl, grid.swr {
+  block-size: 17px;
+}
+grid2 {
+  display: inline-grid;
+  column-gap: 2px;
+  grid-template-columns: 8px 8px;
+  vertical-align: top;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  writing-mode: horizontal-tb;
+  direction: ltr;
+}
+
+grid > div {
+  display: inline-flex;
+  flex-flow: row wrap;
+  inline-size: min-content;
+}
+
+grid2:nth-child(1) { margin-block-end:1px; }
+grid2:nth-child(2) { inline-size: 22px; block-size: 12px; }
+.vll grid2:nth-child(2) { margin-block-start:-4px; grid-template-columns: 12px 8px;}
+.vrr grid2:nth-child(2) { margin-block-start:-4px; grid-template-columns: 12px 8px;}
+.vlr grid2:nth-child(2) { margin-block-start:-4px; grid-template-columns: 12px 8px;}
+.vrl grid2:nth-child(2) { margin-block-start:-4px; grid-template-columns: 12px 8px;}
+.swl grid2:nth-child(2) { margin-block-start:-4px; grid-template-columns: 12px 8px;}
+.swr grid2:nth-child(2) { margin-block-start:-4px; grid-template-columns: 12px 8px;}
+
+.vll grid2:nth-child(1) { inline-size: 22px; }
+.vrr grid2:nth-child(1) { inline-size: 22px; }
+.vlr grid2:nth-child(1) { inline-size: 22px; }
+.vrl grid2:nth-child(1) { inline-size: 22px; }
+.swl grid2:nth-child(1) { inline-size: 22px; }
+.swr grid2:nth-child(1) { inline-size: 22px; }
+
+grid2:nth-child(1) > item:nth-child(1) { background: blue; inline-size:8px; block-size:8px; z-index:1; }
+grid2:nth-child(2) > item:nth-child(1) { background: magenta; inline-size:8px; block-size:12px; z-index:1; }
+grid2:nth-child(1) > item:nth-child(2) { background: lime; inline-size:12px; block-size:8px; z-index:2; }
+grid2:nth-child(2) > item:nth-child(2) { background: purple; inline-size:8px; block-size:8px; z-index:2; }
+</style>
+</head>
+<body>
+<div style="display:none">
+<grid>
+ <div>
+  <grid2>
+    <item></item>
+    <item></item>
+  </grid2><grid2>
+    <item></item>
+    <item></item>
+  </grid2>
+ </div>
+</grid>
+</div>
+
+<script>
+let wms = [ "hl", "hr", "vll", "vrr", "vlr", "vrl", "swl", "swr", ];
+let ats = [ "start", "self-start", "center", "end", "self-end", "stretch", "space-between", "space-around", "space-evenly", ];
+let acs = [ "start", "center", "end", ];
+let grid = document.getElementsByTagName('grid')[0];
+for (const ac of acs) {
+  for (const at of ats) {
+    for (const wm of wms) {
+      let e = grid.cloneNode(true);
+      e.className = wm;
+      e.children[0].children[0].children[0].className = "vrl";
+      e.children[0].children[0].style.justifyContent = at;
+      e.children[0].children[1].style.justifyContent = at;
+      e.style.justifyContent = ac;
+      document.body.appendChild(e);
+    }
+  }
+}
+</script>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-001.html
new file mode 100644
index 00000000000..bfd3c1ca587
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-001.html
@@ -0,0 +1,81 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `justify-tracks` alignment</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-justify-tracks-001-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; direction:ltr; }
+.swr { writing-mode: sideways-lr; direction:rtl; }
+
+grid {
+  display: inline-grid;
+  gap: 1px 2px;
+  grid-template-columns: masonry;
+  grid-template-rows: repeat(2,auto);
+  background: content-box silver;
+  color: #444;
+  padding: 1px 2px;
+  inline-size: 30px;
+  vertical-align: top;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  writing-mode: horizontal-tb;
+  direction: ltr;
+}
+
+item:nth-child(1) { background: blue; inline-size:8px; block-size:8px; }
+item:nth-child(2) { background: magenta; inline-size:8px; block-size:12px; }
+item:nth-child(3) { background: lime; inline-size:12px; block-size:8px; }
+item:nth-child(4) { background: purple; inline-size:8px; block-size:8px; }
+</style>
+</head>
+<body>
+<div style="display:none">
+<grid>
+  <item></item>
+  <item></item>
+  <item></item>
+  <item></item>
+</grid>
+</div>
+
+<script>
+let wms = [ "hl", "hr", "vll", "vrr", "vlr", "vrl", "swl", "swr", ];
+let ats = [ "start", "self-start", "center", "end", "self-end", "stretch", "space-between", "space-around", "space-evenly", ];
+let acs = [ "start", "center", "end", ];
+let grid = document.getElementsByTagName('grid')[0];
+for (const ac of acs) {
+  for (const at of ats) {
+    for (const wm of wms) {
+      let e = grid.cloneNode(true);
+      e.className = wm;
+      e.children[0].className = "vrl";
+      e.style.justifyTracks = at;
+      e.style.justifyContent = ac;
+      document.body.appendChild(e);
+    }
+  }
+}
+</script>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-multi-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-multi-001-ref.html
new file mode 100644
index 00000000000..57176e2b1ec
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-multi-001-ref.html
@@ -0,0 +1,117 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with multiple `justify-tracks` values</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+<style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-columns: auto;
+  grid-template-rows: repeat(8,50px);
+  gap: 3px 5px;
+  padding: 10px 3px 1px 7px;
+  border: solid;
+  border-width: 1px 7px 3px 5px;
+  background: lightgrey content-box;
+  width: 500px;
+  vertical-justify: top;
+}
+.fallback { grid-template-rows:3px; padding:0; border:0; display: grid; }
+item {
+  background: grey;
+  width: 3ch;
+  position: relative;
+  border: 1px solid;
+}
+.purple { background:purple; width:auto; border-left:3px solid; }
+z { display: block; background: yellow; height: calc(.2 * (50px - 2px)); width:calc(.8 * 2ch); }
+a {
+ position: absolute;
+ inset: 0;
+ top: auto;
+ border: 2px solid lime;
+}
+masonry-track {
+  display: grid;
+  grid-auto-flow: column;
+  gap: 3px 5px;
+}
+masonry-track:nth-child(1) { justify-content:start }
+masonry-track:nth-child(2) { justify-content:end }
+masonry-track:nth-child(3) { justify-content:center }
+masonry-track:nth-child(4) { justify-content:stretch; grid-template-columns: repeat(3,auto) repeat(2,max-content); }
+masonry-track:nth-child(5) { justify-content:space-between }
+masonry-track:nth-child(6) { justify-content:space-around }
+masonry-track:nth-child(7) { justify-content:space-evenly }
+masonry-track:nth-child(8) { justify-content:space-evenly }
+</style>
+</head>
+<body>
+<grid>
+ <masonry-track>
+  <item style="width:50px">1</item>
+  <item class="purple">20</item>
+  <item class="purple">26</item>
+  <item>33</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple" style="height:25px">2</item>
+  <item>9<a></a></item>
+  <item class="purple">18</item>
+  <item>25</item>
+ </masonry-track>
+ <masonry-track>
+  <item style="margin-left:10px">3</item>
+  <item>15</item>
+  <item class="purple">24</item>
+  <item class="purple">32</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple" style="margin-top:5px">4</item>
+  <item class="purple">10</item>
+  <item class="purple" style="writing-mode:vertical-rl">16</item>
+  <item>23</item>
+  <item>31</item>
+ </masonry-track>
+ <masonry-track>
+  <item>5</item>
+  <item>13</item>
+  <item class="purple">22</item>
+  <item>29</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">6<a></a></item>
+  <item>11</item>
+  <item>19</item>
+  <item class="purple">28</item>
+ </masonry-track>
+ <masonry-track>
+  <item>7</item>
+  <item class="purple"><z></z>14<a></a></item>
+  <item>21</item>
+  <item class="purple">30</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple" style="writing-mode:vertical-lr">8</item>
+  <item class="purple">12<z></z></item>
+  <item>17</item>
+  <item>27</item>
+ </masonry-track>
+</grid>
+<grid class="fallback" style="justify-content:start">
+  <item></item>
+</grid>
+<grid class="fallback" style="justify-content:center">
+  <item></item>
+</grid>
+<grid class="fallback" style="justify-content:center">
+  <item></item>
+</grid>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-multi-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-multi-001.html
new file mode 100644
index 00000000000..22a41996426
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-multi-001.html
@@ -0,0 +1,91 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with multiple `justify-tracks` values</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-justify-tracks-multi-001-ref.html">
+<style>
+html,body {
+  color:black; background-color:white; font:15px/1 monospace; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-columns: masonry;
+  grid-template-rows: repeat(8,50px); /*intentionally one more than justify-tracks values*/
+  gap: 3px 5px;
+  padding: 10px 3px 1px 7px;
+  border: solid;
+  border-width: 1px 7px 3px 5px;
+  background: lightgrey content-box;
+  justify-tracks: start,end,center,stretch,space-between,space-around,space-evenly;
+  width: 500px;
+  vertical-justify: top;
+}
+.fallback { grid-template-rows:3px; padding:0; border:0; display: grid; }
+item {
+  background: grey;
+  width: 3ch;
+  position: relative;
+  border: 1px solid;
+}
+item:nth-child(2n) { background:purple; width:auto; border-left:3px solid; }
+z { display: block; background: yellow; height: 20%; width:80%; }
+a {
+ position: absolute;
+ inset: 0;
+ top: auto;
+ border: 2px solid lime;
+}
+</style>
+</head>
+<body>
+<grid>
+  <item style="width:10%">1</item>
+  <item style="height:50%">2</item>
+  <item style="margin-left:2%">3</item>
+  <item style="margin-top:1%">4</item>
+  <item>5</item>
+  <item>6<a></a></item>
+  <item>7</item>
+  <item style="writing-mode:vertical-lr">8</item>
+  <item>9<a></a></item>
+  <item>10</item>
+  <item>11</item>
+  <item>12<z></z></item>
+  <item>13</item>
+  <item><z></z>14<a></a></item>
+  <item>15</item>
+  <item style="writing-mode:vertical-rl">16</item>
+  <item>17</item>
+  <item>18</item>
+  <item>19</item>
+  <item>20</item>
+  <item>21</item>
+  <item>22</item>
+  <item>23</item>
+  <item>24</item>
+  <item>25</item>
+  <item>26</item>
+  <item>27</item>
+  <item>28</item>
+  <item>29</item>
+  <item>30</item>
+  <item>31</item>
+  <item>32</item>
+  <item>33</item>
+</grid>
+<grid class="fallback" style="justify-tracks:space-between">
+  <item></item>
+</grid>
+<grid class="fallback" style="justify-tracks:space-around">
+  <item></item>
+</grid>
+<grid class="fallback" style="justify-tracks:space-evenly">
+  <item></item>
+</grid>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-001-ref.html
new file mode 100644
index 00000000000..39053051cc8
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-001-ref.html
@@ -0,0 +1,86 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `justify-tracks:stretch`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+<style>
+html,body {
+  color:black; background-color:white; font:16px/1 Ahem; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-rows: 150px 100px 50px;
+  grid-template-columns: 500px;
+  gap: 5px 3px;
+  padding: 10px;
+  border: 3px solid;
+  background: lightgrey content-box;
+  width: 500px;
+}
+masonry-track {
+  display: grid;
+  gap: 5px 3px;
+  width: 500px;
+}
+masonry-track:nth-child(1) {
+  grid-template-rows: 150px;
+  grid-template-columns: max-content auto auto min-content min-content auto;
+}
+masonry-track:nth-child(2) {
+  grid-template-rows: 100px;
+  grid-template-columns: auto 50px 3ch 3ch 3ch  min-content min-content;
+}
+masonry-track:nth-child(3) {
+  grid-template-rows: 50px;
+  grid-template-columns: 3ch auto 3ch 3ch auto 3ch auto;
+}
+item {
+  background: grey;
+  width: 3ch;
+  position: relative;
+}
+.purple { background:purple; width:auto; }
+z { display: block; background: yellow; width: 20%; height:10%; }
+a {
+ position: absolute;
+ inset: 0;
+ left: auto;
+ border: 2px solid lime;
+}
+</style>
+</head>
+<body>
+<grid>
+ <masonry-track>
+  <item style="border:10px solid; margin:10px 0 5px 3px;">1</item>
+  <item style="writing-mode:vertical-lr" class="purple">8<br>vertical</item>
+  <item class="purple">10</item>
+  <item class="purple" style="width:86px; border:solid; border-width:0 2px; margin-right:1px">12<z></z></item>
+  <item>15</item>
+  <item style="margin:0 auto" class="purple">18</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item style="width:40px; margin-right:10px" class="purple">4</item>
+  <item>5</item>
+  <item>9<a></a></item>
+  <item>13</item>
+  <item style="justify-self:start" class="purple">16</item>
+  <item>19</item>
+ </masonry-track>
+ <masonry-track>
+  <item>3</item>
+  <item class="purple">6<a></a></item>
+  <item>7</item>
+  <item>11</item>
+  <item class="purple">14<z></z><a></a></item>
+  <item>17</item>
+  <item style="margin-left: auto" class="purple">20</item>
+ </masonry-track>
+</grid>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-001.html
new file mode 100644
index 00000000000..17cb3218218
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-001.html
@@ -0,0 +1,67 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `justify-tracks:stretch`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-justify-tracks-stretch-001-ref.html">
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
+<style>
+html,body {
+  color:black; background-color:white; font:16px/1 Ahem; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-rows: 150px 100px 50px;
+  grid-template-columns: masonry;
+  justify-tracks: stretch;
+  gap: 5px 3px;
+  padding: 10px;
+  border: 3px solid;
+  background: lightgrey content-box;
+  width: 500px;
+}
+item {
+  background: grey;
+  width: 3ch;
+  position: relative;
+}
+item:nth-child(2n) { background:purple; width:auto; }
+item:nth-child(1) { border:10px solid; margin: 10px 0 5px 3px; }
+z { display: block; background: yellow; width: 20%; height:10%; }
+a {
+ position: absolute;
+ inset: 0;
+ left: auto;
+ border: 2px solid lime;
+}
+</style>
+</head>
+<body>
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="max-width:40px; margin-right:10px">4</item>
+  <item>5</item>
+  <item>6<a></a></item>
+  <item>7</item>
+  <item style="writing-mode:vertical-lr">8 vertical</item>
+  <item>9<a></a></item>
+  <item>10</item>
+  <item>11</item>
+  <item style="max-width:90px; border:solid; border-width:0 2px; box-sizing:border-box; margin-right:1px">12<z></z></item>
+  <item>13</item>
+  <item>14<z></z><a></a></item>
+  <item>15</item>
+  <item style="justify-self:start">16</item>
+  <item>17</item>
+  <item style="margin:0 auto">18</item>
+  <item>19</item>
+  <item style="margin-left: auto">20</item>
+</grid>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-002-ref.html
new file mode 100644
index 00000000000..69759484f29
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-002-ref.html
@@ -0,0 +1,68 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with `justify-tracks:stretch`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+<style>
+html,body {
+  color:black; background-color:white; font:6px/1 monospace; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-columns: auto auto;
+  grid-template-rows: 30px;
+  gap: 1px 2px;
+  padding: 2px 3px 1px 1px;
+  border-style: solid;
+  border-width: 1px 7px 3px 5px;
+  border-inline-start-color: magenta;
+  border-block-start-color: blue;
+  background: lightgrey content-box;
+  inline-size: 25px;
+  vertical-align: top;
+}
+item {
+  border-inline-start: 1px solid magenta;
+  border-block-start: 2px solid blue;
+}
+item:nth-child(2n+1) { background: grey; }
+item:nth-child(2n) { background: cyan; }
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; direction:ltr; }
+.swr { writing-mode: sideways-lr; direction:rtl; }
+</style>
+</head>
+<body>
+<div style="display:none">
+<grid>
+  <item>1</item>
+  <item>2a<br>2b</item>
+</grid>
+</div>
+<script>
+let wms = [ "hl", "hr", "vll", "vrr", "vlr", "vrl", "swl", "swr", ];
+let grid = document.getElementsByTagName('grid')[0];
+for (const reorder of [false, true]) {
+  for (const cb_wm of wms) {
+    for (const child_wm of wms) {
+      let e = grid.cloneNode(true);
+      e.className = cb_wm;
+      e.children[1].className = child_wm;
+      if (reorder) {
+        e.children[0].style.order = '1';
+      }
+      document.body.appendChild(e);
+    }
+  }
+}
+</script>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-002.html
new file mode 100644
index 00000000000..6b7746722dc
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-justify-tracks-stretch-002.html
@@ -0,0 +1,72 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with `justify-tracks:stretch`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-justify-tracks-stretch-002-ref.html">
+<style>
+html,body {
+  color:black; background-color:white; font:6px/1 monospace; padding:0; margin:0;
+}
+grid {
+  display: inline-grid;
+  grid-template-columns: masonry;
+  grid-template-rows: 30px;
+  gap: 1px 2px;
+  padding: 2px 3px 1px 1px;
+  border-style: solid;
+  border-width: 1px 7px 3px 5px;
+  border-inline-start-color: magenta;
+  border-block-start-color: blue;
+  background: lightgrey content-box;
+  justify-tracks: stretch;
+  inline-size: 25px;
+  vertical-align: top;
+}
+item {
+  position: relative;
+  border-inline-start: 1px solid magenta;
+  border-block-start: 2px solid blue;
+}
+item:nth-child(2n+1) { background: grey; }
+item:nth-child(2n) { background: cyan; }
+.hl { writing-mode: horizontal-tb; direction:ltr; }
+.hr { writing-mode: horizontal-tb; direction:rtl; }
+.vll { writing-mode: vertical-lr; direction:ltr; }
+.vlr { writing-mode: vertical-lr; direction:rtl; }
+.vrl { writing-mode: vertical-rl; direction:ltr; }
+.vrr { writing-mode: vertical-rl; direction:rtl; }
+.swl { writing-mode: sideways-lr; direction:ltr; }
+.swr { writing-mode: sideways-lr; direction:rtl; }
+</style>
+</head>
+<body>
+<div style="display:none">
+<grid>
+  <item>1</item>
+  <item>2a<br>2b</item>
+</grid>
+</div>
+<script>
+let wms = [ "hl", "hr", "vll", "vrr", "vlr", "vrl", "swl", "swr", ];
+let grid = document.getElementsByTagName('grid')[0];
+for (const reorder of [false, true]) {
+  for (const cb_wm of wms) {
+    for (const child_wm of wms) {
+      let e = grid.cloneNode(true);
+      e.className = cb_wm;
+      e.children[1].className = child_wm;
+      if (reorder) {
+        e.children[0].style.order = '1';
+      }
+      document.body.appendChild(e);
+    }
+  }
+}
+</script>
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-001-ref.html
new file mode 100644
index 00000000000..37169998154
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-001-ref.html
@@ -0,0 +1,43 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout using `order`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-template-columns:  repeat(4,auto);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item>1</item>
+  <item style="margin-top:10px">4</item>
+  <item>6</item>
+  <item>2</item>
+  <item>3</item>
+  <item style="grid-column:3/span 2">5</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-001.html
new file mode 100644
index 00000000000..d01f52ea042
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-001.html
@@ -0,0 +1,45 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout using `order`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-order-001-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-template-columns:  repeat(4,auto);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item>1</item>
+  <item style="order:1">2</item>
+  <item style="order:2">3</item>
+  <item style="margin-top:10px">4</item>
+  <item style="order:1; grid-column:span 2">5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-002-ref.html
new file mode 100644
index 00000000000..5dd4e47d80b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-002-ref.html
@@ -0,0 +1,43 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout using `order` and `masonry-auto-flow: next`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-template-columns:  repeat(4,auto);
+  grid-template-rows: masonry;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item>1</item>
+  <item style="margin-top:10px">4</item>
+  <item>6</item>
+  <item>2</item>
+  <item style="grid-column:1/span 2">5</item>
+  <item style="grid-column:3">3</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-002.html
new file mode 100644
index 00000000000..ae68f4e631a
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-order-002.html
@@ -0,0 +1,46 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout using `order` and `masonry-auto-flow: next`</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-order-002-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:25px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  gap: 10px 20px;
+  grid-template-columns:  repeat(4,auto);
+  grid-template-rows: masonry;
+  masonry-auto-flow: next;
+  color: #444;
+  border: 1px solid;
+  padding: 2px;
+}
+
+item {
+  background-color: #444;
+  color: #fff;
+  padding: 20px;
+  margin: 3px;
+  border: 5px solid blue;
+}
+</style>
+</head>
+<body>
+
+<grid>
+  <item>1</item>
+  <item style="order:1">2</item>
+  <item style="order:2">3</item>
+  <item style="margin-top:10px">4</item>
+  <item style="order:1; grid-column:span 2">5</item>
+  <item>6</item>
+</grid>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-parsing.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-parsing.html
new file mode 100644
index 00000000000..e3245095fad
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-parsing.html
@@ -0,0 +1,89 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<title>CSS Masonry Test: parsing properties and shortands</title>
+<link rel="help" href="https://drafts.csswg.org/css-grid-2/#propdef-grid-template-columns">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/css/support/parsing-testcommon.js"></script>
+<script src="/css/support/shorthand-testcommon.js"></script>
+</head>
+<body>
+<script>
+function masonry_test_template_prop(name) {
+  test_valid_value(name, 'masonry');
+  test_invalid_value(name, 'masonry []');
+  test_invalid_value(name, 'masonry [foo] 40px');
+  test_invalid_value(name, 'masonry 40px');
+  test_invalid_value(name, '[foo] masonry');
+  test_invalid_value(name, '0px masonry');
+  test_invalid_value(name, 'masonry masonry');
+  test_invalid_value(name, 'subgrid masonry');
+  test_invalid_value(name, 'masonry subgrid');
+  test_invalid_value(name, 'masonry repeat(1, [])');
+  test_invalid_value(name, 'masonry repeat(auto-fill, [])');
+  test_invalid_value(name, 'masonry / none');
+}
+masonry_test_template_prop("grid-template-columns");
+masonry_test_template_prop("grid-template-rows");
+
+test_shorthand_value("grid-template", 'masonry / masonry', {
+  'grid-template-rows': 'masonry',
+  'grid-template-columns': 'masonry',
+  'grid-template-areas': 'none'
+});
+
+test_shorthand_value("grid-template", 'masonry / subgrid [foo]', {
+  'grid-template-rows': 'masonry',
+  'grid-template-columns': 'subgrid [foo]',
+  'grid-template-areas': 'none'
+});
+
+test_shorthand_value("grid-template", '10px / masonry', {
+  'grid-template-rows': '10px',
+  'grid-template-columns': 'masonry',
+  'grid-template-areas': 'none'
+});
+
+test_shorthand_value("grid", 'masonry / masonry', {
+  'grid-template-rows': 'masonry',
+  'grid-template-columns': 'masonry',
+  'grid-template-areas': 'none',
+  'grid-auto-rows': 'auto',
+  'grid-auto-columns': 'auto',
+  'grid-auto-flow': 'row'
+});
+
+test_shorthand_value("grid", 'masonry / subgrid [foo]', {
+  'grid-template-rows': 'masonry',
+  'grid-template-columns': 'subgrid [foo]',
+  'grid-template-areas': 'none',
+  'grid-auto-rows': 'auto',
+  'grid-auto-columns': 'auto',
+  'grid-auto-flow': 'row'
+});
+
+test_shorthand_value("grid", '10px / masonry', {
+  'grid-template-rows': '10px',
+  'grid-template-columns': 'masonry',
+  'grid-template-areas': 'none',
+  'grid-auto-rows': 'auto',
+  'grid-auto-columns': 'auto',
+  'grid-auto-flow': 'row'
+});
+
+test_valid_value("masonry-auto-flow", 'pack');
+test_valid_value("masonry-auto-flow", 'pack ordered', 'ordered');
+test_valid_value("masonry-auto-flow", 'ordered next', 'next ordered');
+test_valid_value("masonry-auto-flow", 'next definite-first', 'next');
+test_valid_value("masonry-auto-flow", 'definite-first pack', 'pack');
+test_invalid_value("masonry-auto-flow", 'auto');
+test_invalid_value("masonry-auto-flow", 'none');
+test_invalid_value("masonry-auto-flow", '10px');
+test_invalid_value("masonry-auto-flow", 'row');
+test_invalid_value("masonry-auto-flow", 'dense');
+
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-001-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-001-ref.html
new file mode 100644
index 00000000000..25ec77bc518
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-001-ref.html
@@ -0,0 +1,224 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with a subgrid</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+<style>
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  grid-template-rows: 50px 80px 40px;
+  grid-template-columns: auto;
+  gap: 4px 2px;
+  padding: 1px 3px 5px 7px;
+  border: solid;
+  border-width: 3px 5px 1px 1px;
+  background: lightgrey content-box;
+}
+masonry-track {
+  display: grid;
+  gap: 4px 2px;
+}
+masonry-track:nth-child(1) {
+  grid-template-rows: 50px;
+  grid-template-columns: min-content auto;
+}
+masonry-track:nth-child(2) {
+  grid-auto-flow: column;
+  grid-template-rows: 80px 40px;
+  grid-template-columns: auto;
+}
+.rows {
+  grid-template-columns: 50px 122px;
+  grid-template-rows: auto;
+  align-content: start;
+}
+.rows > masonry-track:nth-child(1) {
+  grid-template-columns: 50px;
+  grid-template-rows: auto;
+  align-content: start;
+}
+.rows > masonry-track:nth-child(2) {
+  grid-template-columns: 80px 40px;
+  grid-template-rows: auto;
+  align-content: start;
+}
+item {
+  background: grey;
+  width: 3ch;
+  position: relative;
+}
+.purple { background:purple; width:auto; justify-self:start; }
+.rows .purple { justify-self:stretch; }
+.nth-1 {
+  border: solid;
+  border-width: 3px 13px 1px 1px;
+  margin: 7px 1px 5px 3px;
+}
+subgrid {
+  display: grid;
+  grid: subgrid / 2ch auto;
+  grid-row: 2 / span 2;
+  grid-gap: 8px 20px;
+  background: yellow;
+}
+masonry-track > subgrid {
+  grid-row: 1 / span 2;
+}
+.rows > masonry-track > subgrid {
+  grid: auto auto / subgrid;
+  grid-row: 2;
+  grid-column: 1 / span 2;
+}
+.js { justify-self:stretch; }
+</style>
+</head>
+<body>
+
+<!-- just to sanity check that `masonry` behaves as `none` in the column axis in this case: -->
+<grid style="grid:masonry/none">
+  <item class="nth-1">1</item>
+  <item class="purple js">2</item>
+  <item>3</item>
+  <subgrid style="grid:masonry/none">
+    <item class="nth-1">4a</item>
+    <item style="margin-right:15px" class="purple js">4b</item>
+  </subgrid>
+</grid>
+
+<grid>
+ <masonry-track>
+  <item class="nth-1">1</item>
+  <item>5</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item>3</item>
+  <subgrid>
+    <item class="nth-1" style="grid-column:span 2">4a</item>
+    <item class="purple js">4b</item>
+    <item>4c</item>
+  </subgrid>
+ </masonry-track>
+</grid>
+
+<grid>
+ <masonry-track>
+  <item class="nth-1">1</item>
+  <item>5</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item>3</item>
+  <subgrid style="grid:subgrid/auto">
+    <item class="nth-1">4a</item>
+    <item class="purple js">4b</item>
+    <item>4c</item>
+  </subgrid>
+ </masonry-track>
+</grid>
+
+<grid>
+ <masonry-track>
+  <item class="nth-1">1</item>
+  <item>5</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item>3</item>
+  <subgrid style="grid:subgrid/auto; grid-auto-flow:column">
+    <item class="nth-1">4a</item>
+    <item class="purple js">4b</item>
+    <item>4c</item>
+  </subgrid>
+ </masonry-track>
+</grid>
+
+<grid>
+ <masonry-track>
+  <item class="nth-1">1</item>
+  <item>5</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item>3</item>
+  <subgrid style="grid:auto auto/masonry">
+    <item class="nth-1">4a</item>
+    <item class="purple">4b</item>
+    <item>4c</item>
+  </subgrid>
+ </masonry-track>
+</grid>
+
+<grid class="rows">
+ <masonry-track>
+  <item class="nth-1">1</item>
+  <item>5</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item>3</item>
+  <subgrid>
+    <item class="nth-1" style="grid-row:span 2; align-self:start">4a</item>
+    <item class="purple">4b</item>
+    <item style="grid-column:2">4c</item>
+  </subgrid>
+ </masonry-track>
+</grid>
+
+<grid class="rows">
+ <masonry-track>
+  <item class="nth-1">1</item>
+  <item>5</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item>3</item>
+  <subgrid style="grid:auto/subgrid">
+    <item class="nth-1">4a</item>
+    <item class="purple">4b</item>
+    <item>4c</item>
+  </subgrid>
+ </masonry-track>
+</grid>
+
+<grid class="rows">
+ <masonry-track>
+  <item class="nth-1">1</item>
+  <item>5</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item>3</item>
+  <subgrid style="grid:auto/subgrid; grid-auto-flow:column">
+    <item class="nth-1">4a</item>
+    <item class="purple">4b</item>
+    <item>4c</item>
+  </subgrid>
+ </masonry-track>
+</grid>
+
+<grid class="rows">
+ <masonry-track>
+  <item class="nth-1">1</item>
+  <item>5</item>
+ </masonry-track>
+ <masonry-track>
+  <item class="purple">2</item>
+  <item>3</item>
+  <subgrid style="grid:auto auto/subgrid">
+    <item class="nth-1">4a</item>
+    <item class="purple">4b</item>
+    <item>4c</item>
+  </subgrid>
+ </masonry-track>
+</grid>
+
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-001.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-001.html
new file mode 100644
index 00000000000..de07dfb78d1
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-001.html
@@ -0,0 +1,164 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with a subgrid</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-subgrid-001-ref.html">
+<style>
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  grid-template-rows: 50px 80px 40px;
+  grid-template-columns: masonry;
+  gap: 4px 2px;
+  padding: 1px 3px 5px 7px;
+  border: solid;
+  border-width: 3px 5px 1px 1px;
+  background: lightgrey content-box;
+}
+.rows {
+  grid-template-columns: 50px 80px 40px;
+  grid-template-rows: masonry;
+}
+item {
+  background: grey;
+  width: 3ch;
+  position: relative;
+}
+item:nth-child(2n) { background:purple; width:auto; }
+item:nth-child(1) {
+  border: solid;
+  border-width: 3px 13px 1px 1px;
+  margin: 7px 1px 5px 3px;
+}
+subgrid {
+  display: grid;
+  grid: subgrid / subgrid;
+  grid-row: 2 / span 2;
+  grid-gap: 8px 20px;
+  background: yellow;
+}
+.rows > subgrid {
+  grid-row: initial;
+  grid-column: 2 / span 2;
+}
+</style>
+</head>
+<body>
+
+<!-- just to sanity check that `masonry` behaves as `none` in the column axis in this case: -->
+<grid style="grid:masonry/masonry">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid>
+    <item>4a</item>
+    <item style="margin-right:15px">4b</item>
+  </subgrid>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid>
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid:subgrid/auto">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid:subgrid/auto; grid-auto-flow:column">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid:auto auto/subgrid">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid>
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid:auto/subgrid">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid:auto/subgrid; grid-auto-flow:column">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid:auto auto/subgrid">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-002-ref.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-002-ref.html
new file mode 100644
index 00000000000..4750c1899e3
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-002-ref.html
@@ -0,0 +1,302 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Masonry layout with a subgrid</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+<style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  grid-template-rows: 40px 30px 20px;
+  grid-template-columns: masonry;
+  gap: 4px 2px;
+  padding: 1px 3px 5px 7px;
+  border: solid;
+  border-width: 3px 5px 1px 1px;
+  background: lightgrey content-box;
+  grid-auto-flow: column;
+}
+.rows {
+  grid-template-columns: 40px 30px 20px;
+  grid-template-rows: masonry;
+  grid-auto-flow: row;
+}
+item {
+  background: grey;
+  width: 3ch;
+  position: relative;
+}
+item:nth-child(2n) { background:purple; width:auto; }
+item:nth-child(1) {
+  border: solid;
+  border-width: 3px 5px 1px 1px;
+  margin: 7px 1px 5px 3px;
+}
+subgrid {
+  display: grid;
+  grid-row: auto/span 2;
+  grid-column: auto/span 2;
+  grid: subgrid / subgrid;
+  grid-gap: 6px 8px;
+  background: yellow;
+}
+subgrid.definite {
+  grid-row-start:2;
+}
+subgrid.extent {
+  grid-row: 1/span 3;
+}
+.rows > subgrid.definite {
+  grid-column-start:2;
+  grid-row-start:auto;
+}
+.rows > subgrid.extent {
+  grid-row: auto/span 2;
+  grid-column: 1/span 3;
+}
+</style>
+</head>
+<body>
+
+<!-- auto-placed subgrid inhibits subgridding when parent is doing masonry layout ... -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: none / masonry">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... unless it's auto-placed in the first track ... -->
+<grid>
+  <item>1</item>
+  <subgrid class="definite">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>2</item>
+  <item>3</item>
+  <item>5</item>
+</grid>
+
+<!-- ... or has definite start position -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: 29px 19px / masonry">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... or span all tracks in the grid-axis -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="extent" style="grid: 39px 28px 19px / masonry">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid inhibits subgridding when parent is doing masonry layout ... -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: none / masonry">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... unless it's auto-placed in the first track ... -->
+<grid>
+  <item>1</item>
+  <subgrid class="definite">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>2</item>
+  <item>3</item>
+  <item>5</item>
+</grid>
+
+<!-- ... or has definite start position -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: 29px 19px / masonry">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... or span all tracks in the grid-axis -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="extent" style="grid: 39px 28px 19px / masonry">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid "inherits" masonry if it has a grid-axis of its own -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: auto auto / masonry">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid inhibits subgridding when parent is doing masonry layout ... -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: masonry / none">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... unless it's auto-placed in the first track ... -->
+<grid class="rows">
+  <item>1</item>
+  <subgrid class="definite">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>2</item>
+  <item>3</item>
+  <item>5</item>
+</grid>
+
+<!-- ... or has definite start position -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: masonry / 27px 17px">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... or span all tracks in the grid-axis -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="extent" style="grid: masonry / 37px 24px 17px">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid inhibits subgridding when parent is doing masonry layout -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: masonry / none">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... unless it's auto-placed in the first track ... -->
+<grid class="rows">
+  <item>1</item>
+  <subgrid class="definite">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>2</item>
+  <item>3</item>
+  <item>5</item>
+</grid>
+
+<!-- ... or has definite start position -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: masonry / 27px 17px">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... or span all tracks in the grid-axis -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="extent" style="grid: masonry / 37px 24px 17px">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid "inherits" masonry if it has a grid-axis of its own -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: masonry / auto auto">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-002.html b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-002.html
new file mode 100644
index 00000000000..466e95eb03c
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/masonry.tentative/masonry-subgrid-002.html
@@ -0,0 +1,301 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Masonry layout with a subgrid</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drats.csswg.org/css-grid-2">
+  <link rel="match" href="masonry-subgrid-002-ref.html">
+<style>
+html,body {
+  color:black; background-color:white; font:10px/1 monospace; padding:0; margin:0;
+}
+
+grid {
+  display: inline-grid;
+  grid-template-rows: 40px 30px 20px;
+  grid-template-columns: masonry;
+  gap: 4px 2px;
+  padding: 1px 3px 5px 7px;
+  border: solid;
+  border-width: 3px 5px 1px 1px;
+  background: lightgrey content-box;
+}
+.rows {
+  grid-template-columns: 40px 30px 20px;
+  grid-template-rows: masonry;
+}
+item {
+  background: grey;
+  width: 3ch;
+  position: relative;
+}
+item:nth-child(2n) { background:purple; width:auto; }
+item:nth-child(1) {
+  border: solid;
+  border-width: 3px 5px 1px 1px;
+  margin: 7px 1px 5px 3px;
+}
+subgrid {
+  display: grid;
+  grid-row: auto/span 2;
+  grid-column: auto/span 2;
+  grid: subgrid / subgrid;
+  grid-gap: 6px 8px;
+  background: yellow;
+}
+subgrid.definite {
+  grid-row-start:2;
+}
+subgrid.extent {
+  grid-row: auto/span 3;
+}
+.rows > subgrid.definite {
+  grid-column-start:2;
+}
+.rows > subgrid.extent {
+  grid-row: auto/span 2;
+  grid-column: auto/span 3;
+}
+</style>
+</head>
+<body>
+
+<!-- auto-placed subgrid inhibits subgridding when parent is doing masonry layout ... -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid>
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... unless it's auto-placed in the first track ... -->
+<grid>
+  <item>1</item>
+  <subgrid>
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>2</item>
+  <item>3</item>
+  <item>5</item>
+</grid>
+
+<!-- ... or has definite start position -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="definite">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... or span all tracks in the grid-axis -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="extent">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid inhibits subgridding when parent is doing masonry layout ... -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: subgrid / masonry">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... unless it's auto-placed in the first track ... -->
+<grid>
+  <item>1</item>
+  <subgrid style="grid: subgrid / masonry">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>2</item>
+  <item>3</item>
+  <item>5</item>
+</grid>
+
+<!-- ... or has definite start position -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="definite">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... or span all tracks in the grid-axis -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="extent">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid "inherits" masonry if it has a grid-axis of its own -->
+<grid>
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: auto auto / subgrid">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid inhibits subgridding when parent is doing masonry layout ... -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid>
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... unless it's auto-placed in the first track ... -->
+<grid class="rows">
+  <item>1</item>
+  <subgrid>
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>2</item>
+  <item>3</item>
+  <item>5</item>
+</grid>
+
+<!-- ... or has definite start position -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="definite">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... or span all tracks in the grid-axis -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="extent">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid inhibits subgridding when parent is doing masonry layout -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: masonry / subgrid">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... unless it's auto-placed in the first track ... -->
+<grid class="rows">
+  <item>1</item>
+  <subgrid style="grid: masonry / subgrid">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>2</item>
+  <item>3</item>
+  <item>5</item>
+</grid>
+
+<!-- ... or has definite start position -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="definite">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- ... or span all tracks in the grid-axis -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid class="extent">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+<!-- auto-placed subgrid "inherits" masonry if it has a grid-axis of its own -->
+<grid class="rows">
+  <item>1</item>
+  <item>2</item>
+  <item>3</item>
+  <subgrid style="grid: subgrid / auto auto">
+    <item>4a</item>
+    <item>4b</item>
+    <item>4c</item>
+  </subgrid>
+  <item>5</item>
+</grid>
+
+</body></html>
diff --git a/tests/wpt/web-platform-tests/css/css-images/image-orientation/reference/svg-image-orientation-none-ref.html b/tests/wpt/web-platform-tests/css/css-images/image-orientation/reference/svg-image-orientation-none-ref.html
new file mode 100644
index 00000000000..c7feb1dfeec
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-images/image-orientation/reference/svg-image-orientation-none-ref.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<title>CSS Images Module Level 3: svg image ignores orientation with image-orientation:none: Reference</title>
+<link rel="author" title="Stephen Chenney" href="mailto:schenney@chromium.org">
+</head>
+<body>
+    <svg style="width: 500px; height: 650px;">
+        <image xlink:href="../support/exif-orientation-1-ul.jpg" X="0" Y="0"></image>
+        <image xlink:href="../support/exif-orientation-1-ul.jpg" X="125" Y="0"></image>
+        <image xlink:href="../support/exif-orientation-1-ul.jpg" X="250" Y="0"></image>
+        <image xlink:href="../support/exif-orientation-1-ul.jpg" X="375" Y="0"></image>
+        <image xlink:href="../support/exif-orientation-1-ul.jpg" X="0" Y="125"></image>
+        <image xlink:href="../support/exif-orientation-1-ul.jpg" X="125" Y="125"></image>
+        <image xlink:href="../support/exif-orientation-1-ul.jpg" X="250" Y="125"></image>
+        <image xlink:href="../support/exif-orientation-1-ul.jpg" X="375" Y="125"></image>
+        <image xlink:href="../support/exif-orientation-1-ul.jpg" X="0" Y="250"></image>
+    </svg>
+</body>
+</html>
\ No newline at end of file
diff --git a/tests/wpt/web-platform-tests/css/css-images/image-orientation/svg-image-orientation-none.html b/tests/wpt/web-platform-tests/css/css-images/image-orientation/svg-image-orientation-none.html
new file mode 100644
index 00000000000..a89de9df7de
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-images/image-orientation/svg-image-orientation-none.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<title>CSS Images Module Level 3: svg image ignores orientation with image-orientation:none</title>
+<link rel="author" title="Stephen Chenney" href="mailto:schenney@chromium.org">
+<link rel="help" href="https://drafts.csswg.org/css-images-3/#propdef-image-orientation">
+<link rel="match" href="reference/svg-image-orientation-none-ref.html">
+<meta name=fuzzy content="10;100">
+</head>
+<body>
+    <svg style="width: 500px; height: 650px; image-orientation: none;">
+        <image xlink:href="support/exif-orientation-1-ul.jpg" X="0" Y="0"></image>
+        <image xlink:href="support/exif-orientation-2-ur.jpg" X="125" Y="0"></image>
+        <image xlink:href="support/exif-orientation-3-lr.jpg" X="250" Y="0"></image>
+        <image xlink:href="support/exif-orientation-4-lol.jpg" X="375" Y="0"></image>
+        <image xlink:href="support/exif-orientation-5-lu.jpg" X="0" Y="125"></image>
+        <image xlink:href="support/exif-orientation-6-ru.jpg" X="125" Y="125"></image>
+        <image xlink:href="support/exif-orientation-7-rl.jpg" X="250" Y="125"></image>
+        <image xlink:href="support/exif-orientation-8-llo.jpg" X="375" Y="125"></image>
+        <image xlink:href="support/exif-orientation-9-u.jpg" X="0" Y="250"></image>
+    </svg>
+</body>
+</html>
\ No newline at end of file
diff --git a/tests/wpt/web-platform-tests/css/css-speech/Integer.html b/tests/wpt/web-platform-tests/css/css-speech/voice-family-integer.html
similarity index 100%
rename from tests/wpt/web-platform-tests/css/css-speech/Integer.html
rename to tests/wpt/web-platform-tests/css/css-speech/voice-family-integer.html
diff --git a/tests/wpt/web-platform-tests/css/css-text-decor/text-underline-offset-invalid.html b/tests/wpt/web-platform-tests/css/css-text-decor/text-underline-offset-invalid.html
index c60f9d595bc..9f77be0359f 100644
--- a/tests/wpt/web-platform-tests/css/css-text-decor/text-underline-offset-invalid.html
+++ b/tests/wpt/web-platform-tests/css/css-text-decor/text-underline-offset-invalid.html
@@ -19,10 +19,6 @@ test_invalid_value("text-underline-offset", "60002020");
 test_invalid_value("text-underline-offset", "!@#$%^&");
 test_invalid_value("text-underline-offset", "10e2");
 test_invalid_value("text-underline-offset", "from font");
-test_invalid_value("text-underline-offset", "10%");
-test_invalid_value("text-underline-offset", "-27%");
-test_invalid_value("text-underline-offset", "calc(40% - 20px)");
-test_invalid_value("text-underline-offset", "calc(100% - 40em)");
 </script>
 </body>
 </html>
diff --git a/tests/wpt/web-platform-tests/css/css-transforms/animation/rotate-interpolation.html b/tests/wpt/web-platform-tests/css/css-transforms/animation/rotate-interpolation.html
index eff60ba72f7..0d80d8ffad1 100644
--- a/tests/wpt/web-platform-tests/css/css-transforms/animation/rotate-interpolation.html
+++ b/tests/wpt/web-platform-tests/css/css-transforms/animation/rotate-interpolation.html
@@ -4,8 +4,9 @@
 <meta charset="utf-8">
 <title>rotate interpolation</title>
 <link rel="help" href="https://drafts.csswg.org/css-transforms-2/#propdef-rotate">
-
 <meta name="assert" content="rotate supports animation.">
+<meta name="timeout" content="long">
+
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script src="/css/support/interpolation-testcommon.js"></script>
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/the-stylepropertymap/properties/text-underline-offset.html b/tests/wpt/web-platform-tests/css/css-typed-om/the-stylepropertymap/properties/text-underline-offset.html
new file mode 100644
index 00000000000..0e54ea8f5a4
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/the-stylepropertymap/properties/text-underline-offset.html
@@ -0,0 +1,22 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>'text-underline-offset' property</title>
+<link rel="help" href="https://drafts.css-houdini.org/css-typed-om-1/#dom-stylepropertymap-get">
+<link rel="help" href="https://drafts.css-houdini.org/css-typed-om-1/#dom-stylepropertymap-set">
+<link rel="help" href="https://drafts.css-houdini.org/css-typed-om-1/#property-stle-value-normalization">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../../resources/testhelper.js"></script>
+<script src="resources/testsuite.js"></script>
+<body>
+<div id="log"></div>
+<script>
+'use strict';
+
+runPropertyTests('text-underline-offset', [
+  { syntax: 'auto' },
+  { syntax: '<length>' },
+  { syntax: '<percentage>' },
+]);
+
+</script>
diff --git a/tests/wpt/web-platform-tests/docs/writing-tests/testharness.md b/tests/wpt/web-platform-tests/docs/writing-tests/testharness.md
index e04a344d098..1e9772a4017 100644
--- a/tests/wpt/web-platform-tests/docs/writing-tests/testharness.md
+++ b/tests/wpt/web-platform-tests/docs/writing-tests/testharness.md
@@ -116,8 +116,8 @@ creating a `FileAPI/FileReaderSync.worker.js` as follows:
 ```js
 importScripts("/resources/testharness.js");
 test(function () {
-    var blob = new Blob(["Hello"]);
-    var fr = new FileReaderSync();
+    const blob = new Blob(["Hello"]);
+    const fr = new FileReaderSync();
     assert_equals(fr.readAsText(blob), "Hello");
 }, "FileReaderSync#readAsText.");
 done();
@@ -138,7 +138,7 @@ creating a `FileAPI/Blob-constructor.any.js` as follows:
 
 ```js
 test(function () {
-    var blob = new Blob();
+    const blob = new Blob();
     assert_equals(blob.size, 0);
     assert_equals(blob.type, "");
     assert_false(blob.isClosed);
@@ -152,16 +152,13 @@ It is possible to customize the set of scopes with a metadata comment, such as
 
 ```
 // META: global=sharedworker
-//       ==> would run in the default window and dedicated worker scopes,
-//           as well as the shared worker scope
-// META: global=!default,serviceworker
-//       ==> would only run in the service worker scope
-// META: global=!window
-//       ==> would run in the default dedicated worker scope, but not the
-//           window scope
+//       ==> would run in the shared worker scope
+// META: global=window,serviceworker
+//       ==> would only run in the window and service worker scope
+// META: global=dedicatedworker
+//       ==> would run in the default dedicated worker scope
 // META: global=worker
-//       ==> would run in the default window scope, as well as in the
-//           dedicated, shared and service worker scopes
+//       ==> would run in the dedicated, shared, and service worker scopes
 ```
 
 For a test file <code><var>x</var>.any.js</code>, the available scope keywords
@@ -173,8 +170,7 @@ are:
 * `sharedworker`: to be run at <code><var>x</var>.any.sharedworker.html</code>
 * `jsshell`: to be run in a JavaScript shell, without access to the DOM
   (currently only supported in SpiderMonkey, and skipped in wptrunner)
-* `default`: shorthand for the default scopes
-* `worker`: shorthand for the dedicated, shared and service worker scopes
+* `worker`: shorthand for the dedicated, shared, and service worker scopes
 
 To check if your test is run from a window or worker you can use the following two methods that will
 be made available by the framework:
diff --git a/tests/wpt/web-platform-tests/dom/idlharness.any.js b/tests/wpt/web-platform-tests/dom/idlharness.any.js
index 5119f9f9754..26da3ab3bf9 100644
--- a/tests/wpt/web-platform-tests/dom/idlharness.any.js
+++ b/tests/wpt/web-platform-tests/dom/idlharness.any.js
@@ -1,4 +1,4 @@
-// META: global=!window,worker
+// META: global=worker
 // META: script=/resources/WebIDLParser.js
 // META: script=/resources/idlharness.js
 // META: timeout=long
diff --git a/tests/wpt/web-platform-tests/event-timing/crossiframe.html b/tests/wpt/web-platform-tests/event-timing/crossiframe.html
index 0376fb91f94..dfbd2897ad4 100644
--- a/tests/wpt/web-platform-tests/event-timing/crossiframe.html
+++ b/tests/wpt/web-platform-tests/event-timing/crossiframe.html
@@ -51,13 +51,18 @@
   promise_test(async t => {
     assert_implements(window.PerformanceEventTiming, "Event Timing is not supported");
     clickTimeMin = performance.now();
-    let observedEntries = false;
+    let observedMouseDown = false;
     const observerPromise = new Promise(resolve => {
       new PerformanceObserver(t.step_func(entries => {
-        assert_false(observedEntries,
+        const mouseDowns = entries.getEntriesByName('mousedown');
+        // Ignore the callback if there were no mousedown entries.
+        if (mouseDowns.length === 0)
+          return;
+
+        assert_false(observedMouseDown,
             "Observer of main frames should only capture main-frame event-timing entries");
-        validateEntries(entries.getEntriesByName('mousedown'));
-        observedEntries = true;
+        validateEntries(mouseDowns);
+        observedMouseDown = true;
         resolve();
       })).observe({type: 'event'});
     });
diff --git a/tests/wpt/web-platform-tests/event-timing/event-click-counts.html b/tests/wpt/web-platform-tests/event-timing/event-click-counts.html
index d4e87c58969..6c6563b9581 100644
--- a/tests/wpt/web-platform-tests/event-timing/event-click-counts.html
+++ b/tests/wpt/web-platform-tests/event-timing/event-click-counts.html
@@ -22,10 +22,6 @@
       assert_equals(clickCount, expectedCount,'Incorrect click count.');
       assert_equals(performance.eventCounts.get('mousedown'), expectedCount, 'Incorrect mousedown count');
       assert_equals(performance.eventCounts.get('mouseup'), expectedCount, 'Incorrect mouseup count.');
-      assert_equals(performance.eventCounts.get('mouseover'), expectedCount, 'Incorrect mouseover count.');
-      if (expectedCount != 1) {
-        assert_equals(performance.eventCounts.get('mouseout'), expectedCount - 1, 'Incorrect mouseout count.');
-      }
       resolve();
     }
     function promiseClicks(expectedCount) {
diff --git a/tests/wpt/web-platform-tests/event-timing/event-retarget.html b/tests/wpt/web-platform-tests/event-timing/event-retarget.html
index 130e70092b2..29c114f356b 100644
--- a/tests/wpt/web-platform-tests/event-timing/event-retarget.html
+++ b/tests/wpt/web-platform-tests/event-timing/event-retarget.html
@@ -23,12 +23,16 @@ async_test(function(t) {
       };
     }
   });
-  const observer = new PerformanceObserver(t.step_func_done((entryList) => {
-    const entries = entryList.getEntries().filter(e => e.name === 'mousedown');
-    // There must only be one click entry.
+  const observer = new PerformanceObserver(t.step_func((entryList) => {
+    const entries = entryList.getEntriesByName('mousedown');
+    if (entries.length === 0)
+      return;
+
+    // There must only be one mousedown entry.
     assert_equals(entries.length, 1);
     verifyClickEvent(entries[0], 'custom_button', true);
     assert_true(innerButtonClicked);
+    t.done()
   }));
   observer.observe({entryTypes: ['event']});
   clickAndBlockMain('custom_button');
diff --git a/tests/wpt/web-platform-tests/event-timing/programmatic-click-not-observed.html b/tests/wpt/web-platform-tests/event-timing/programmatic-click-not-observed.html
index b5b1683bd4c..4060d2d00dc 100644
--- a/tests/wpt/web-platform-tests/event-timing/programmatic-click-not-observed.html
+++ b/tests/wpt/web-platform-tests/event-timing/programmatic-click-not-observed.html
@@ -17,25 +17,35 @@
     while(performance.now() < end) {}
     delayCalled = true;
   }
-  async_test(function(t) {
+  promise_test(function(t) {
     assert_implements(window.PerformanceEventTiming, 'Event Timing is not supported.');
-    const observer = new PerformanceObserver(t.step_func_done((entryList) => {
-      const entries = entryList.getEntries().filter(e => e.name === 'mousedown');
-      // There must only be one click entry: from the clickAndBlockMain() call.
-      assert_equals(entries.length, 1);
-      const entry = entries[0];
-      // This ensures that the entry is exposing timing from the second click, i.e.
-      // the one from the clickAndBlockMain() call.
-      assert_greater_than_equal(entry.processingStart, beforeClick);
-      verifyClickEvent(entry, 'div2', true);
-    }));
-    observer.observe({entryTypes: ['event']});
+    let observedMouseDown = false;
+    const observerPromise = new Promise(resolve => {
+      const observer = new PerformanceObserver(t.step_func(entryList => {
+        const mouseDowns = entryList.getEntriesByName('mousedown');
+        // Ignore cases in which there is no mousedown.
+        if (mouseDowns.length === 0)
+          return;
+
+        assert_false(observedMouseDown, 'There must only be one mousedown entry.');
+        assert_equals(mouseDowns.length, 1);
+        const entry = mouseDowns[0];
+        // This ensures that the entry is exposing timing from the second click, i.e.
+        // the one from the clickAndBlockMain() call.
+        assert_greater_than_equal(entry.processingStart, beforeClick);
+        verifyClickEvent(entry, 'div2', true);
+        observedMouseDown = true;
+        resolve();
+      }));
+      observer.observe({entryTypes: ['event']});
+    });
     document.getElementById('div').click();
     // Take the timestamp after the programmatic click but before the next click.
     beforeClick = performance.now();
     // After the programmatic click, use another input to know when entries have been
     // dispatched to the PerformanceObserver callback.
-    clickAndBlockMain('div2');
+    const clickPromise = clickAndBlockMain('div2');
+    return Promise.all([observerPromise, clickPromise]);
   }, "Event Timing: events from programmatic click are not observed");
 </script>
 </html>
diff --git a/tests/wpt/web-platform-tests/event-timing/retrievability.html b/tests/wpt/web-platform-tests/event-timing/retrievability.html
index 087cd13184b..d5a9c04df82 100644
--- a/tests/wpt/web-platform-tests/event-timing/retrievability.html
+++ b/tests/wpt/web-platform-tests/event-timing/retrievability.html
@@ -31,9 +31,11 @@
   */
   async_test(function(t) {
     assert_implements(window.PerformanceEventTiming, 'Event Timing is not supported.');
-    new PerformanceObserver(t.step_func_done(() => {
-      validateEntries();
-      t.done();
+    new PerformanceObserver(t.step_func(entryList => {
+      if (entryList.getEntriesByName('mousedown')) {
+        validateEntries();
+        t.done();
+      }
     })).observe({entryTypes: ['event']});
     clickAndBlockMain('button');
   }, "Event Timing: make sure event-timing entries are not retrievable by performance.getEntries*.");
diff --git a/tests/wpt/web-platform-tests/event-timing/timingconditions.html b/tests/wpt/web-platform-tests/event-timing/timingconditions.html
index e7763c40dc0..5f4448c2a10 100644
--- a/tests/wpt/web-platform-tests/event-timing/timingconditions.html
+++ b/tests/wpt/web-platform-tests/event-timing/timingconditions.html
@@ -32,28 +32,38 @@
     target.focus();
   }
 
-  async_test(function(t) {
+  promise_test(function(t) {
     assert_implements(window.PerformanceEventTiming, 'Event Timing is not supported.');
-    new PerformanceObserver(t.step_func_done(entryList => {
-      const observerCallbackTime = performance.now();
-      const entries = entryList.getEntries().filter(
-          entry => entry.name === 'mousedown');
-      assert_equals(entries.length, 1,
-          "Should only observe one entry: " +
-          JSON.stringify(entries) + ".");
-      assert_equals(entries[0].name, 'mousedown',
-          "The observed entry should be a click");
-      assert_less_than(entries[0].startTime, observerCallbackTime,
-          "The startTime should be before observerCallbackTime");
-      assert_greater_than(entries[0].startTime, trustedClickStart,
-          "The startTime should be after trustedClickStart");
-    })).observe({ entryTypes: ['event'] });
+    let observedMouseDown = false;
+    const observerPromise = new Promise(resolve => {
+      new PerformanceObserver(t.step_func(entryList => {
+        const observerCallbackTime = performance.now();
+        const mouseDowns = entryList.getEntriesByName('mousedown');
+        // Ignore cases in which there is no mousedown.
+        if (mouseDowns.length === 0)
+          return;
+
+        assert_false(observedMouseDown, 'Got more than one callback with mousedown.');
+        assert_equals(mouseDowns.length, 1,
+            "Should only observe one mousedown entry. Instead, got these: " +
+            JSON.stringify(mouseDowns) + ".");
+        assert_equals(mouseDowns[0].name, 'mousedown',
+            "The observed entry should be a mousedown");
+        assert_less_than(mouseDowns[0].startTime, observerCallbackTime,
+            "The startTime should be before observerCallbackTime");
+        assert_greater_than(mouseDowns[0].startTime, trustedClickStart,
+            "The startTime should be after trustedClickStart");
+        observedMouseDown = true;
+        resolve();
+      })).observe({ entryTypes: ['event'] });
+    });
     // Untrusted event of a type event timing cares about.
     untrustedClickAndBlockMain('button');
     // Trusted event of a type event timing doesn't cares about.
     trustedFocusAndBlockMain('button');
     // Trusted event of a type event timing cares about.
-    trustedClickAndBlockMain('button').then(wait);
+    const clickPromise = trustedClickAndBlockMain('button').then(wait);
+    return Promise.all([observerPromise, clickPromise]);
   }, "Event Timing only times certain types of trusted event.");
 </script>
 </html>
diff --git a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-disabled-image-tentative.sub.html b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-disabled-image-tentative.sub.html
index 5bd9fca2a86..e5bb5d39f80 100644
--- a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-disabled-image-tentative.sub.html
+++ b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-disabled-image-tentative.sub.html
@@ -1,6 +1,6 @@
 <!doctype html>
 <meta charset=utf-8>
-<title>Verify behavior of 'lazyload' attribute state 'OFF' when the feature policy 'lazyload' is
+<title>Verify behavior of 'loading' attribute state 'eager' when the feature policy 'lazyload' is
        disabled.
 </title>
 <link rel="stylesheet" href="/feature-policy/experimental-features/resources/lazyload-image.css">
@@ -27,34 +27,30 @@ img {
 <body>
   <p>Image inserted further below.</p>
   <div id="image-container">
-    <img id="off" lazyload="off" src="http://{{hosts[alt][www1]}}:{{ports[http][0]}}/feature-policy/experimental-features/resources/lazyload.png"></img>
+    <img id="eager" loading="eager" src="http://{{hosts[alt][www1]}}:{{ports[http][0]}}/feature-policy/experimental-features/resources/lazyload.png"></img>
     <img id="auto" lazyload="auto" src="http://{{hosts[alt][www2]}}:{{ports[http][0]}}/feature-policy/experimental-features/resources/lazyload.png"></img>
   </div>
   <script>
-    var img_off = document.getElementById("off");
+    var img_eager = document.getElementById("eager");
     var img_auto = document.getElementById("auto");
-    [window, img_off, img_auto].forEach((target) => {
+    [window, img_eager, img_auto].forEach((target) => {
       target.load_complete = wait_for_load(target).then(() => target.did_load = true );
     });
 
-    function images_loaded() {
-      return img_off.did_load && img_auto.did_load;
-    }
-
     function same_load_state() {
-      return img_off.did_load === img_auto.did_load;
+      return img_eager.did_load === img_auto.did_load;
     }
 
-    // Verifies that "off" and "auto" behave the same for out-of-view images.
+    // Verifies that "eager" and "auto" behave the same for out-of-view images.
     promise_test(async(t) => {
       await window.load_complete;
       assert_true(same_load_state(), "Expected same loading state for both images.");
-    }, "When the 'lazyload' feature is disabled, lazyload=OFF and lazyload=AUTO behave the same.");
+    }, "When the 'lazyload' feature is disabled, lazyload=EAGER and lazyload=AUTO behave the same.");
 
-    // Verifies that images with attributes "off" and "auto" load after the images get into view.
+    // Verifies that images with attributes "eager" and "auto" load after the images get into view.
     promise_test(async(t) => {
       document.getElementById("image-container").scrollIntoView();
-      await img_off.load_complete;
+      await img_eager.load_complete;
       await img_auto.load_complete;
     },  "Sanity-check: Verify that all images load after they are scrolled into view.");
   </script>
diff --git a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-disabled-tentative.sub.html b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-disabled-tentative.sub.html
index b6a5d9374ce..2ffcba71cea 100644
--- a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-disabled-tentative.sub.html
+++ b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-disabled-tentative.sub.html
@@ -30,54 +30,54 @@ iframe {
 
   window.scrollTo(0, 0);
 
-  // Sanity-check: Make sure lazyload='on' works as intended.
+  // Sanity-check: Make sure loading='lazy' works as intended.
   promise_test(async(t) => {
-    // Add a frame with lazyload="on".
-    let frame_on = createIframe(document.body, {
-        id: "ON",
-        lazyload: "on",
-        src: `${cross_origin_url}?id=ON`
+    // Add a frame with loading="lazy".
+    let frame_lazy = createIframe(document.body, {
+        id: "LAZY",
+        loading: "lazy",
+        src: `${cross_origin_url}?id=LAZY`
       });
     // Sanity-check: The frame is not visible.
     assert_greater_than(
-        frame_on.getBoundingClientRect().top,
+        frame_lazy.getBoundingClientRect().top,
         window.innerHeight * 2,
-        "Unexpected position for <iframe> with ID 'ON'.");
-    let msg_or_timeout_attr_on =
-        await waitForMessageOrTimeout(t, "ON", load_timeout);
-    assert_equals(msg_or_timeout_attr_on,
+        "Unexpected position for <iframe> with ID 'LAZY'.");
+    let msg_or_timeout_attr_lazy =
+        await waitForMessageOrTimeout(t, "LAZY", load_timeout);
+    assert_equals(msg_or_timeout_attr_lazy,
                   expected_timeout_msg,
-                  "With lazyload='on', the frame should not load.");
+                  "With loading='lazy', the frame should not load.");
   }, "Sanity-check: Contents do not load immediately (no eager-loading) " +
-     "when the lazyload attribute is 'on' and frame is in viewport.");
+     "when the loading attribute is 'lazy' and frame is in viewport.");
 
 
-  // Verify that when 'lazyload' policy is disabled,  lazyload='off' and
-  // lazyload='auto' behave the same.
+  // Verify that when 'lazyload' policy is disabled,  loading='eager' and
+  // loading='auto' behave the same.
   promise_test(async(t) => {
-    // Add a frame with lazyload="off".
-    let frame_on = createIframe(document.body, {
-        id: "OFF",
-        lazyload: "off",
-        src: `${cross_origin_url}?id=OFF`
+    // Add a frame with loading="eager".
+    let frame_lazy = createIframe(document.body, {
+        id: "EAGER",
+        loading: "eager",
+        src: `${cross_origin_url}?id=EAGER`
       });
     // Sanity-check: The frame is not visible.
     assert_greater_than(
-        frame_on.getBoundingClientRect().top,
+        frame_lazy.getBoundingClientRect().top,
         window.innerHeight * 2,
-        "Unexpected position for <iframe> with ID 'OFF'.");
-    let msg_or_timeout_attr_off =
-        await waitForMessageOrTimeout(t, "OFF", load_timeout);
+        "Unexpected position for <iframe> with ID 'EAGER'.");
+    let msg_or_timeout_attr_eager =
+        await waitForMessageOrTimeout(t, "EAGER", load_timeout);
 
-    // Now do the same for lazyload='auto'.
+    // Now do the same for loading='auto'.
     let frame_auto = createIframe(document.body, {
         id: "AUTO",
-        lazyload: "auto",
+        loading: "auto",
         src: `${cross_origin_url}?id=AUTO`
     });
     // Sanity-check: The frame is not visible.
     assert_greater_than(
-        frame_on.getBoundingClientRect().top,
+        frame_lazy.getBoundingClientRect().top,
         window.innerHeight * 2,
         "Unexpected position for <iframe> with ID 'AUTO'.");
     let msg_or_timeout_attr_auto =
@@ -85,9 +85,9 @@ iframe {
 
     // The result should be the same.
     assert_equals(
-          msg_or_timeout_attr_off,
+          msg_or_timeout_attr_eager,
           msg_or_timeout_attr_auto,
-          "lazyload='off' not treated as 'auto'.");
+          "loading='eager' not treated as 'auto'.");
   }, "When 'lazyload' feature is disabled, a frame cannot avoid lazyloading " +
-     "by setting 'lazyload' attribute to 'off'");
+     "by setting 'loading' attribute to 'eager'");
 </script>
diff --git a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-enabled-image-tentative.sub.html b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-enabled-image-tentative.sub.html
index a9e2b295d50..8983762c31b 100644
--- a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-enabled-image-tentative.sub.html
+++ b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-enabled-image-tentative.sub.html
@@ -1,6 +1,6 @@
 <!doctype html>
 <meta charset=utf-8>
-<title>Verify behavior of 'lazyload' attribute state 'OFF' when the feature policy 'lazyload' is
+<title>Verify behavior of 'lazyload' attribute state 'eager' when the feature policy 'lazyload' is
        enabled.
 </title>
 <script src="/resources/testharness.js"></script>
@@ -26,7 +26,7 @@ img {
 <body>
   <p>Image inserted further below.</p>
   <div id="image-container">
-    <img id="off" loading="eager" src="http://{{hosts[alt][www1]}}:{{ports[http][0]}}/feature-policy/experimental-features/resources/lazyload.png"></img>
+    <img loading="eager" src="http://{{hosts[alt][www1]}}:{{ports[http][0]}}/feature-policy/experimental-features/resources/lazyload.png"></img>
   </div>
   <script>
     var img = document.querySelector("img");
diff --git a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-enabled-tentative.sub.html b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-enabled-tentative.sub.html
index 3a2f469b250..d1171b5d06c 100644
--- a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-enabled-tentative.sub.html
+++ b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-enabled-tentative.sub.html
@@ -53,7 +53,7 @@ iframe {
      "when the loading attribute is 'lazy' and frame is in viewport.");
 
   // When feature is enabled, a frame can turn off lazy loading by setting the
-  // attribute to 'off'.
+  // attribute to 'eager'.
   promise_test(async(t) => {
     // Add a frame with loading="eager".
     let frame_off = createIframe(document.body, {
diff --git a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-image-attribute-on-sanity-check-tentative.sub.html b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-image-loading-lazy-tentative.sub.html
similarity index 65%
rename from tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-image-attribute-on-sanity-check-tentative.sub.html
rename to tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-image-loading-lazy-tentative.sub.html
index a913158982e..8f1ef1968ea 100644
--- a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-image-attribute-on-sanity-check-tentative.sub.html
+++ b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/lazyload-image-loading-lazy-tentative.sub.html
@@ -1,6 +1,6 @@
 <!doctype html>
 <meta charset=utf-8>
-<title>Verify behavior of 'lazyload' attribute state 'ON' (sanity-check for lazyload policy tests).
+<title>Verify behavior of 'loading' attribute state 'LAZY' (sanity-check for lazyload policy tests).
 </title>
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
@@ -25,7 +25,7 @@ img {
 <body>
   <p>Image inserted further below.</p>
   <div id="image-container">
-    <img lazyload="on" src="http://{{hosts[alt][www1]}}:{{ports[http][0]}}/feature-policy/experimental-features/resources/lazyload.png"/>
+    <img loading="lazy" src="http://{{hosts[alt][www1]}}:{{ports[http][0]}}/feature-policy/experimental-features/resources/lazyload.png"/>
   </div>
   <script>
     var img = document.querySelector("img");
@@ -35,14 +35,15 @@ img {
       target.load_complete = wait_for_load(target).then(() => target.did_load = true );
     });
 
-    // Sanity-check: Verify that when feature-policy 'lazyload' is enabled, the lazyload attribute
-    // value 'OFF' works as expected (images load immediately).
+    // Verify that when feature-policy 'lazyload' is enabled, the loading
+    // attribute value 'LAZY' works as expected (images load only when scrolled
+    // down).
     promise_test( async(t) => {
       await window.load_complete;
       assert_false(img.did_load, "Out-of-viewport image should not have loaded.");
       img.scrollIntoView();
       await img.load_complete;
-    }, "Verify 'lazyload' attribute state 'on' works as expected: image loads only when in " +
+    }, "Verify 'loading' attribute state 'lazy' works as expected: image loads only when in " +
        "viewport.");
  </script>
 </body>
diff --git a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/loading-frame-default-eager-disabled-tentative.sub.html b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/loading-frame-default-eager-disabled-tentative.sub.html
index 2a6faefcd3b..fe249634f4e 100644
--- a/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/loading-frame-default-eager-disabled-tentative.sub.html
+++ b/tests/wpt/web-platform-tests/feature-policy/experimental-features/lazyload/loading-frame-default-eager-disabled-tentative.sub.html
@@ -33,7 +33,6 @@ iframe {
   // Verify that when 'loading-frame-default-eager' policy is disabled, the
   // loading attribute "auto" leads to lazy loading.
   promise_test(async(t) => {
-    // Add a frame with load="off".
     let frame_loading_auto = createIframe(document.body, {
         id: "auto",
         // Sets the "loading" attribute to "auto".
diff --git a/tests/wpt/web-platform-tests/html/rendering/replaced-elements/the-select-element/select-multiple-re-add-option-via-document-fragment-ref.html b/tests/wpt/web-platform-tests/html/rendering/replaced-elements/the-select-element/select-multiple-re-add-option-via-document-fragment-ref.html
new file mode 100644
index 00000000000..cb66ddaaaf3
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/rendering/replaced-elements/the-select-element/select-multiple-re-add-option-via-document-fragment-ref.html
@@ -0,0 +1,4 @@
+<!doctype html>
+<title>Reference: Move option from select[multiple] into DocumentFragment and back</title>
+<p>You should see the word PASS below.</p>
+<select multiple><option>PASS</option></select>
diff --git a/tests/wpt/web-platform-tests/html/rendering/replaced-elements/the-select-element/select-multiple-re-add-option-via-document-fragment.html b/tests/wpt/web-platform-tests/html/rendering/replaced-elements/the-select-element/select-multiple-re-add-option-via-document-fragment.html
new file mode 100644
index 00000000000..844f05639c9
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/rendering/replaced-elements/the-select-element/select-multiple-re-add-option-via-document-fragment.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<title>Test: Move option from select[multiple] into DocumentFragment and back</title>
+<link rel="help" href="https://html.spec.whatwg.org/multipage/rendering.html#the-select-element-2">
+<link rel="match" href="select-multiple-re-add-option-via-document-fragment-ref.html">
+<p>You should see the word PASS below.</p>
+<select multiple id="sel"><option id="opt">PASS</option></select>
+<script>
+  document.body.offsetTop;
+  let rm = opt;
+  document.createDocumentFragment().appendChild(rm);
+  sel.appendChild(rm);
+</script>
diff --git a/tests/wpt/web-platform-tests/html/webappapis/scripting/processing-model-2/integration-with-the-javascript-agent-formalism/requires-failure.https.any.js b/tests/wpt/web-platform-tests/html/webappapis/scripting/processing-model-2/integration-with-the-javascript-agent-formalism/requires-failure.https.any.js
index 8b688403671..fddf85dbede 100644
--- a/tests/wpt/web-platform-tests/html/webappapis/scripting/processing-model-2/integration-with-the-javascript-agent-formalism/requires-failure.https.any.js
+++ b/tests/wpt/web-platform-tests/html/webappapis/scripting/processing-model-2/integration-with-the-javascript-agent-formalism/requires-failure.https.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,window,serviceworker
+// META: global=window,serviceworker
 
 test(() => {
   // See https://github.com/whatwg/html/issues/5380 for why not `new SharedArrayBuffer()`
diff --git a/tests/wpt/web-platform-tests/html/webappapis/scripting/processing-model-2/integration-with-the-javascript-agent-formalism/requires-success.any.js b/tests/wpt/web-platform-tests/html/webappapis/scripting/processing-model-2/integration-with-the-javascript-agent-formalism/requires-success.any.js
index 9adc044a0dd..0da449a7cff 100644
--- a/tests/wpt/web-platform-tests/html/webappapis/scripting/processing-model-2/integration-with-the-javascript-agent-formalism/requires-success.any.js
+++ b/tests/wpt/web-platform-tests/html/webappapis/scripting/processing-model-2/integration-with-the-javascript-agent-formalism/requires-success.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,dedicatedworker,sharedworker
+// META: global=dedicatedworker,sharedworker
 
 test(() => {
   // See https://github.com/whatwg/html/issues/5380 for why not `new SharedArrayBuffer()`
diff --git a/tests/wpt/web-platform-tests/html/webappapis/system-state-and-capabilities/the-navigator-object/navigator_user_agent.https.html b/tests/wpt/web-platform-tests/html/webappapis/system-state-and-capabilities/the-navigator-object/navigator_user_agent.https.html
index 9a22728ec7e..a8ed461b2e7 100644
--- a/tests/wpt/web-platform-tests/html/webappapis/system-state-and-capabilities/the-navigator-object/navigator_user_agent.https.html
+++ b/tests/wpt/web-platform-tests/html/webappapis/system-state-and-capabilities/the-navigator-object/navigator_user_agent.https.html
@@ -9,6 +9,7 @@
   }, "navigator.userAgentData is exposed.");
 
   promise_test(async t => {
+    let didMicrotaskRun = false;
     const uaData = navigator.userAgentData;
     for (brandVersionPair of uaData.brands) {
       assert_equals(typeof brandVersionPair.brand, "string", "brand should be a string");
@@ -25,5 +26,12 @@
     assert_equals(highEntropyData2["platformVersion"], "", "Platform version should be an empty string");
     assert_equals(highEntropyData2["architecture"], "", "Architecture should be an empty string");
     assert_equals(highEntropyData2["model"], "", "Model should be an empty string");
+    let  finalPromise = uaData.getHighEntropyValues([]).then(() => {
+      assert_true(didMicrotaskRun, "getHighEntropyValues queued on a task");
+    });
+    await Promise.resolve().then(function() {
+      didMicrotaskRun = true;
+    });
+    return finalPromise;
   }, "navigator.userAgentData returns a UserAgentMetadata object.");
 </script>
diff --git a/tests/wpt/web-platform-tests/native-io/close_sync.tentative.https.any.js b/tests/wpt/web-platform-tests/native-io/close_sync.tentative.https.any.js
index 0cfc9de2ec6..8897d66f2cc 100644
--- a/tests/wpt/web-platform-tests/native-io/close_sync.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/native-io/close_sync.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Synchronous NativeIO API: close().
-// META: global=!default,dedicatedworker
+// META: global=dedicatedworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/native-io/delete_sync_basic.tentative.https.any.js b/tests/wpt/web-platform-tests/native-io/delete_sync_basic.tentative.https.any.js
index c9c600d6b16..8e033bbc429 100644
--- a/tests/wpt/web-platform-tests/native-io/delete_sync_basic.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/native-io/delete_sync_basic.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Synchronous NativeIO API: File deletion is reflected in listing.
-// META: global=!default,dedicatedworker
+// META: global=dedicatedworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/native-io/open_getAll_sync_basic.tentative.https.any.js b/tests/wpt/web-platform-tests/native-io/open_getAll_sync_basic.tentative.https.any.js
index 64fa90182a6..fc73a0471cf 100644
--- a/tests/wpt/web-platform-tests/native-io/open_getAll_sync_basic.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/native-io/open_getAll_sync_basic.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Synchronous NativeIO API: File creation is reflected in listing.
-// META: global=!default,dedicatedworker
+// META: global=dedicatedworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/native-io/read_write_sync_basic.tentative.https.any.js b/tests/wpt/web-platform-tests/native-io/read_write_sync_basic.tentative.https.any.js
index f6265aa83f5..d46e0120b68 100644
--- a/tests/wpt/web-platform-tests/native-io/read_write_sync_basic.tentative.https.any.js
+++ b/tests/wpt/web-platform-tests/native-io/read_write_sync_basic.tentative.https.any.js
@@ -1,5 +1,5 @@
 // META: title=Synchronous NativeIO API: Written bytes are read back.
-// META: global=!default,dedicatedworker
+// META: global=dedicatedworker
 
 'use strict';
 
diff --git a/tests/wpt/web-platform-tests/pointerevents/pointerevent_touch-action-none-on-body-when-style-propagates-to-viewport_touch.html b/tests/wpt/web-platform-tests/pointerevents/pointerevent_touch-action-none-on-body-when-style-propagates-to-viewport_touch.html
index e1b9d50ec59..b2a3a9326ea 100644
--- a/tests/wpt/web-platform-tests/pointerevents/pointerevent_touch-action-none-on-body-when-style-propagates-to-viewport_touch.html
+++ b/tests/wpt/web-platform-tests/pointerevents/pointerevent_touch-action-none-on-body-when-style-propagates-to-viewport_touch.html
@@ -83,7 +83,7 @@
       }).then(
         ()=>{t.done();},
         ()=>{t.done();}
-      );});
+      );}, "touch-action none on body when style propagates to viewport");
     }
   </script>
 </body>
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/ServiceWorkerGlobalScope/fetch-on-the-right-interface.https.any.js b/tests/wpt/web-platform-tests/service-workers/service-worker/ServiceWorkerGlobalScope/fetch-on-the-right-interface.https.any.js
index 44946d43b62..e98a04b6a09 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/ServiceWorkerGlobalScope/fetch-on-the-right-interface.https.any.js
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/ServiceWorkerGlobalScope/fetch-on-the-right-interface.https.any.js
@@ -1,5 +1,5 @@
 // META: title=fetch method on the right interface
-// META: global=!default,serviceworker
+// META: global=serviceworker
 
 test(function() {
     assert_false(self.hasOwnProperty('fetch'), 'ServiceWorkerGlobalScope ' +
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/global-serviceworker.https.any.js b/tests/wpt/web-platform-tests/service-workers/service-worker/global-serviceworker.https.any.js
index 2335f635b2e..19d77847c42 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/global-serviceworker.https.any.js
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/global-serviceworker.https.any.js
@@ -1,5 +1,5 @@
 // META: title=serviceWorker on service worker global
-// META: global=!default,serviceworker
+// META: global=serviceworker
 
 test(() => {
   assert_equals(registration.installing, null, 'registration.installing');
diff --git a/tests/wpt/web-platform-tests/shadow-dom/declarative/declarative-shadow-dom-attachment.tentative.html b/tests/wpt/web-platform-tests/shadow-dom/declarative/declarative-shadow-dom-attachment.tentative.html
index 0acdeb812ec..33997b09ab7 100644
--- a/tests/wpt/web-platform-tests/shadow-dom/declarative/declarative-shadow-dom-attachment.tentative.html
+++ b/tests/wpt/web-platform-tests/shadow-dom/declarative/declarative-shadow-dom-attachment.tentative.html
@@ -70,12 +70,10 @@ function testElementType(allowed, nochildren, elementType, mode, delegatesFocus)
 }
 
 function runAllTests() {
-  const noChildElements = ['iframe','noscript','script','select','style','textarea','title'];
   const noCheck = ['body'];
   const safelisted = ATTACHSHADOW_SAFELISTED_ELEMENTS.filter(el => !noCheck.includes(el));
   const disallowed = ATTACHSHADOW_DISALLOWED_ELEMENTS.filter(el => !noCheck.includes(el));
-  const minimumKnownElements = 113; // We should have at least this many elements in the lists from shadow-dom-utils.js.
-  assert_true(safelisted.length + disallowed.length + noChildElements.length >= minimumKnownElements,'All element types should be tested');
+  const noChildElements = ['iframe','noscript','script','select','style','textarea','title'];
   for (let delegatesFocus of [false, true]) {
     for (let mode of ['open', 'closed', 'invalid']) {
       for (let elementName of safelisted) {
diff --git a/tests/wpt/web-platform-tests/shadow-dom/declarative/declarative-shadow-dom-basic.tentative.html b/tests/wpt/web-platform-tests/shadow-dom/declarative/declarative-shadow-dom-basic.tentative.html
index 9ba98777769..332c0e1cd3e 100644
--- a/tests/wpt/web-platform-tests/shadow-dom/declarative/declarative-shadow-dom-basic.tentative.html
+++ b/tests/wpt/web-platform-tests/shadow-dom/declarative/declarative-shadow-dom-basic.tentative.html
@@ -26,6 +26,10 @@ test(() => {
   assert_array_equals(s1.assignedNodes(), [c1]);
 }, 'Declarative Shadow DOM: Basic test');
 
+test(() => {
+  assert_true(HTMLTemplateElement.prototype.hasOwnProperty("shadowRoot"),'Unable to feature detect');
+}, 'Declarative Shadow DOM: Feature detection');
+
 test(() => {
   const div = document.createElement('div');
   div.innerHTML = `
diff --git a/tests/wpt/web-platform-tests/shadow-dom/declarative/getinnerhtml.tentative.html b/tests/wpt/web-platform-tests/shadow-dom/declarative/getinnerhtml.tentative.html
new file mode 100644
index 00000000000..25af077d94f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/shadow-dom/declarative/getinnerhtml.tentative.html
@@ -0,0 +1,60 @@
+<!DOCTYPE html>
+<title>getInnerHTML </title>
+<link rel='author' title='Mason Freed' href='mailto:masonfreed@chromium.org'>
+<link rel='help' href='https://github.com/whatwg/dom/issues/831'>
+<script src='/resources/testharness.js'></script>
+<script src='/resources/testharnessreport.js'></script>
+<script src='../resources/shadow-dom-utils.js'></script>
+
+<body>
+
+<script>
+function testElementType(allowsShadowDom, elementType, mode, delegatesFocus) {
+  var t = test(t => {
+    // Create and attach element
+    const wrapper = document.createElement('div');
+    t.add_cleanup(function() { wrapper.remove(); });
+    document.body.appendChild(wrapper);
+    const element = document.createElement(elementType);
+    wrapper.appendChild(element);
+
+    const isOpen = mode === 'open';
+    if (allowsShadowDom) {
+      let correctShadowHtml = isOpen ? `<template shadowroot="${mode}"><slot></slot></template>` : '';
+      let correctHtml = `<${elementType}>${correctShadowHtml}</${elementType}>`;
+      const shadowRoot = element.attachShadow({mode: mode, delegatesFocus: delegatesFocus});
+      shadowRoot.appendChild(document.createElement('slot'));
+      assert_equals(wrapper.getInnerHTML({includeShadowRoots: true}),correctHtml);
+      assert_equals(wrapper.getInnerHTML(),correctHtml,'The default for includeShadowRoots should be true');
+    } else {
+      // For non-shadow hosts, getInnerHTML() should also match .innerHTML
+      assert_equals(wrapper.getInnerHTML({includeShadowRoots: true}),wrapper.innerHTML);
+      assert_equals(wrapper.getInnerHTML(),wrapper.innerHTML);
+    }
+
+    // Either way, make sure getInnerHTML({includeShadowRoots: false}) matches .innerHTML
+    assert_equals(wrapper.getInnerHTML({includeShadowRoots: false}),wrapper.innerHTML,'getInnerHTML() with includeShadowRoots false should return the same as .innerHTML');
+
+  }, `getInnerHTML() on <${elementType}>${allowsShadowDom ? `, with mode=${mode}, delegatesFocus=${delegatesFocus}.` : ''}`);
+}
+
+function runAllTests() {
+  const allElements = HTML5_ELEMENT_NAMES;
+  const safelisted = ATTACHSHADOW_SAFELISTED_ELEMENTS;
+  for (let elementName of allElements) {
+    const allowsShadowDom = safelisted.includes(elementName);
+    if (allowsShadowDom) {
+      for (let delegatesFocus of [false, true]) {
+        for (let mode of ['open', 'closed']) {
+          testElementType(true, elementName, mode, delegatesFocus);
+        }
+      }
+    } else {
+      testElementType(false, elementName);
+    }
+  }
+}
+
+runAllTests();
+
+</script>
diff --git a/tests/wpt/web-platform-tests/shadow-dom/declarative/script-access.tentative.html b/tests/wpt/web-platform-tests/shadow-dom/declarative/script-access.tentative.html
index 3ecfce55aa3..250a03601a5 100644
--- a/tests/wpt/web-platform-tests/shadow-dom/declarative/script-access.tentative.html
+++ b/tests/wpt/web-platform-tests/shadow-dom/declarative/script-access.tentative.html
@@ -20,11 +20,13 @@ function myObserver(mutationsList, observer) {
             assert_in_array(shadowroot, ['open','closed'], 'Declarative template should have shadowroot attribute');
             assert_equals(n.content, null, 'Declarative template content should be null');
             assert_equals(n.innerHTML, "", 'Declarative template innerHTML should be empty');
+            assert_equals(n.getInnerHTML({includeShadowRoots: true}), "", 'Declarative template getInnerHTML() should be empty');
 
             // Make sure removing the shadowroot attribute doesn't affect things.
             n.removeAttribute('shadowroot');
             assert_equals(n.content, null, 'Declarative template content should *still* be null');
             assert_equals(n.innerHTML, "", 'Declarative template innerHTML should *still* be empty');
+            assert_equals(n.getInnerHTML({includeShadowRoots: true}), "", 'Declarative template getInnerHTML() should *still* be empty');
             break;
           case 'noroot':
             // Make sure adding 'shadowroot' attribute doesn't trigger a shadow root,
@@ -32,6 +34,7 @@ function myObserver(mutationsList, observer) {
             n.setAttribute('shadowroot','open');
             assert_not_equals(n.content, null, 'Regular template should have content, even after adding shadowroot attribute');
             assert_not_equals(n.innerHTML, "", 'Regular template should have innerHTML, even after adding shadowroot attribute');
+            assert_not_equals(n.getInnerHTML({includeShadowRoots: true}), "", 'Regular template should have getInnerHTML(), even after adding shadowroot attribute');
             break;
           default:
             assert_unreached('Unrecognized template');
diff --git a/tests/wpt/web-platform-tests/tools/lint/lint.py b/tests/wpt/web-platform-tests/tools/lint/lint.py
index 1762049d198..fad93662a44 100644
--- a/tests/wpt/web-platform-tests/tools/lint/lint.py
+++ b/tests/wpt/web-platform-tests/tools/lint/lint.py
@@ -20,7 +20,7 @@ from ..gitignore.gitignore import PathFilter
 from ..wpt import testfiles
 from ..manifest.vcs import walk
 
-from ..manifest.sourcefile import SourceFile, js_meta_re, python_meta_re, space_chars, get_any_variants, get_default_any_variants
+from ..manifest.sourcefile import SourceFile, js_meta_re, python_meta_re, space_chars, get_any_variants
 from six import binary_type, iteritems, itervalues, with_metaclass
 from six.moves import range
 from six.moves.urllib.parse import urlsplit, urljoin
@@ -611,28 +611,10 @@ def check_global_metadata(value):
     # type: (str) -> Iterable[Tuple[Type[rules.Rule], Tuple[Any, ...]]]
     global_values = {item.strip() for item in value.split(b",") if item.strip()}
 
-    included_variants = set.union(get_default_any_variants(),
-                                  *(get_any_variants(v) for v in global_values if not v.startswith(b"!")))
-
+    # TODO: this could check for duplicates and such
     for global_value in global_values:
-        if global_value.startswith(b"!"):
-            excluded_value = global_value[1:]
-            if not get_any_variants(excluded_value):
-                yield (rules.UnknownGlobalMetadata, ())
-
-            elif excluded_value in global_values:
-                yield (rules.BrokenGlobalMetadata,
-                       (("Cannot specify both %s and %s" % (global_value, excluded_value)),))
-
-            else:
-                excluded_variants = get_any_variants(excluded_value)
-                if not (excluded_variants & included_variants):
-                    yield (rules.BrokenGlobalMetadata,
-                           (("Cannot exclude %s if it is not included" % (excluded_value,)),))
-
-        else:
-            if not get_any_variants(global_value):
-                yield (rules.UnknownGlobalMetadata, ())
+        if not get_any_variants(global_value):
+            yield (rules.UnknownGlobalMetadata, ())
 
 
 def check_script_metadata(repo_root, path, f):
diff --git a/tests/wpt/web-platform-tests/tools/lint/tests/test_file_lints.py b/tests/wpt/web-platform-tests/tools/lint/tests/test_file_lints.py
index 72d4a05c902..b06104db694 100644
--- a/tests/wpt/web-platform-tests/tools/lint/tests/test_file_lints.py
+++ b/tests/wpt/web-platform-tests/tools/lint/tests/test_file_lints.py
@@ -844,17 +844,17 @@ def test_script_metadata(filename, input, error):
 
 @pytest.mark.parametrize("globals,error", [
     (b"", None),
-    (b"default", None),
-    (b"!default", None),
+    (b"default", "UNKNOWN-GLOBAL-METADATA"),
+    (b"!default", "UNKNOWN-GLOBAL-METADATA"),
     (b"window", None),
-    (b"!window", None),
-    (b"!dedicatedworker", None),
-    (b"window, !window", "BROKEN-GLOBAL-METADATA"),
-    (b"!serviceworker", "BROKEN-GLOBAL-METADATA"),
-    (b"serviceworker, !serviceworker", "BROKEN-GLOBAL-METADATA"),
-    (b"worker, !dedicatedworker", None),
-    (b"worker, !serviceworker", None),
-    (b"!worker", None),
+    (b"!window", "UNKNOWN-GLOBAL-METADATA"),
+    (b"!dedicatedworker", "UNKNOWN-GLOBAL-METADATA"),
+    (b"window, !window", "UNKNOWN-GLOBAL-METADATA"),
+    (b"!serviceworker", "UNKNOWN-GLOBAL-METADATA"),
+    (b"serviceworker, !serviceworker", "UNKNOWN-GLOBAL-METADATA"),
+    (b"worker, !dedicatedworker", "UNKNOWN-GLOBAL-METADATA"),
+    (b"worker, !serviceworker", "UNKNOWN-GLOBAL-METADATA"),
+    (b"!worker", "UNKNOWN-GLOBAL-METADATA"),
     (b"foo", "UNKNOWN-GLOBAL-METADATA"),
     (b"!foo", "UNKNOWN-GLOBAL-METADATA"),
 ])
diff --git a/tests/wpt/web-platform-tests/tools/manifest/sourcefile.py b/tests/wpt/web-platform-tests/tools/manifest/sourcefile.py
index 15dc9151248..d0794a2851e 100644
--- a/tests/wpt/web-platform-tests/tools/manifest/sourcefile.py
+++ b/tests/wpt/web-platform-tests/tools/manifest/sourcefile.py
@@ -74,7 +74,6 @@ def read_script_metadata(f, regexp):
 
 
 _any_variants = {
-    b"default": {"longhand": {b"window", b"dedicatedworker"}},
     b"window": {"suffix": ".any.html"},
     b"serviceworker": {"force_https": True},
     b"sharedworker": {},
@@ -90,7 +89,6 @@ def get_any_variants(item):
     Returns a set of variants (bytestrings) defined by the given keyword.
     """
     assert isinstance(item, binary_type), item
-    assert not item.startswith(b"!"), item
 
     variant = _any_variants.get(item, None)
     if variant is None:
@@ -104,7 +102,7 @@ def get_default_any_variants():
     """
     Returns a set of variants (bytestrings) that will be used by default.
     """
-    return set(_any_variants[b"default"]["longhand"])
+    return set({b"window", b"dedicatedworker"})
 
 
 def parse_variants(value):
@@ -114,15 +112,13 @@ def parse_variants(value):
     """
     assert isinstance(value, binary_type), value
 
-    globals = get_default_any_variants()
+    if value == b"":
+        return get_default_any_variants()
 
+    globals = set()
     for item in value.split(b","):
         item = item.strip()
-        if item.startswith(b"!"):
-            globals -= get_any_variants(item[1:])
-        else:
-            globals |= get_any_variants(item)
-
+        globals |= get_any_variants(item)
     return globals
 
 
diff --git a/tests/wpt/web-platform-tests/tools/manifest/tests/test_sourcefile.py b/tests/wpt/web-platform-tests/tools/manifest/tests/test_sourcefile.py
index 6ee6e2b3dff..a8887e4078e 100644
--- a/tests/wpt/web-platform-tests/tools/manifest/tests/test_sourcefile.py
+++ b/tests/wpt/web-platform-tests/tools/manifest/tests/test_sourcefile.py
@@ -328,25 +328,10 @@ test()"""
 
 
 @pytest.mark.parametrize("input,expected", [
-    (b"", {"dedicatedworker", "window"}),
-    (b"default", {"dedicatedworker", "window"}),
-    (b"!default", {}),
-    (b"!default,window", {"window"}),
-    (b"window,!default", {}),
-    (b"!default,dedicatedworker", {"dedicatedworker"}),
-    (b"dedicatedworker,!default", {}),
-    (b"!default,worker", {"dedicatedworker", "serviceworker", "sharedworker"}),
-    (b"worker,!default", {"serviceworker", "sharedworker"}),
-    (b"!dedicatedworker", {"window"}),
-    (b"!worker", {"window"}),
-    (b"!window", {"dedicatedworker"}),
-    (b"!window,worker", {"dedicatedworker", "serviceworker", "sharedworker"}),
-    (b"worker,!dedicatedworker", {"serviceworker", "sharedworker", "window"}),
-    (b"!dedicatedworker,worker", {"dedicatedworker", "serviceworker", "sharedworker", "window"}),
-    (b"worker,!sharedworker", {"dedicatedworker", "serviceworker", "window"}),
-    (b"!sharedworker,worker", {"dedicatedworker", "serviceworker", "sharedworker", "window"}),
-    (b"sharedworker", {"dedicatedworker", "sharedworker", "window"}),
-    (b"sharedworker,serviceworker", {"dedicatedworker", "serviceworker", "sharedworker", "window"}),
+    (b"window", {"window"}),
+    (b"sharedworker", {"sharedworker"}),
+    (b"sharedworker,serviceworker", {"serviceworker", "sharedworker"}),
+    (b"worker", {"dedicatedworker", "serviceworker", "sharedworker"}),
 ])
 def test_multi_global_with_custom_globals(input, expected):
     contents = b"""// META: global=%s
@@ -384,7 +369,7 @@ test()""" % input
 
 
 def test_multi_global_with_jsshell_globals():
-    contents = b"""// META: global=jsshell
+    contents = b"""// META: global=window,dedicatedworker,jsshell
 test()"""
 
     s = create("html/test.any.js", contents=contents)
diff --git a/tests/wpt/web-platform-tests/url/url-setters-stripping.any.js b/tests/wpt/web-platform-tests/url/url-setters-stripping.any.js
new file mode 100644
index 00000000000..3413c6cd5ad
--- /dev/null
+++ b/tests/wpt/web-platform-tests/url/url-setters-stripping.any.js
@@ -0,0 +1,125 @@
+function urlString({ scheme = "https",
+                     username = "username",
+                     password = "password",
+                     host = "host",
+                     port = "8000",
+                     pathname = "path",
+                     search = "query",
+                     hash = "fragment" }) {
+  return `${scheme}://${username}:${password}@${host}:${port}/${pathname}?${search}#${hash}`;
+}
+
+function urlRecord(scheme) {
+  return new URL(urlString({ scheme }));
+}
+
+for(const scheme of ["https", "wpt++"]) {
+  for(let i = 0; i < 0x20; i++) {
+    const stripped = i === 0x09 || i === 0x0A || i === 0x0D;
+
+    // It turns out that user agents are surprisingly similar for these ranges so generate fewer
+    // tests. If this is changed also change the logic for host below.
+    if (i !== 0 && i !== 0x1F && !stripped) {
+      continue;
+    }
+
+    const cpString = String.fromCodePoint(i);
+    const cpReference = "U+" + i.toString(16).toUpperCase().padStart(4, "0");
+
+    test(() => {
+      const expected = scheme === "https" ? (stripped ? "http" : "https") : (stripped ? "wpt--" : "wpt++");
+      const url = urlRecord(scheme);
+      url.protocol = String.fromCodePoint(i) + (scheme === "https" ? "http" : "wpt--");
+      assert_equals(url.protocol, expected + ":", "property");
+      assert_equals(url.href, urlString({ scheme: expected }), "href");
+    }, `Setting protocol with leading ${cpReference} (${scheme}:)`);
+
+    test(() => {
+      const expected = scheme === "https" ? (stripped ? "http" : "https") : (stripped ? "wpt--" : "wpt++");
+      const url = urlRecord(scheme);
+      url.protocol = (scheme === "https" ? "http" : "wpt--") + String.fromCodePoint(i);
+      assert_equals(url.protocol, expected + ":", "property");
+      assert_equals(url.href, urlString({ scheme: expected }), "href");
+    }, `Setting protocol with ${cpReference} before inserted colon (${scheme}:)`);
+
+    // Cannot test protocol with trailing as the algorithm inserts a colon before proceeding
+
+    // These do no stripping
+    for (const property of ["username", "password"]) {
+      for (const [type, expected, input] of [
+        ["leading", encodeURIComponent(cpString) + "test", String.fromCodePoint(i) + "test"],
+        ["middle", "te" + encodeURIComponent(cpString) + "st", "te" + String.fromCodePoint(i) + "st"],
+        ["trailing", "test" + encodeURIComponent(cpString), "test" + String.fromCodePoint(i)]
+      ]) {
+        test(() => {
+          const url = urlRecord(scheme);
+          url[property] = input;
+          assert_equals(url[property], expected, "property");
+          assert_equals(url.href, urlString({ scheme, [property]: expected }), "href");
+        }, `Setting ${property} with ${type} ${cpReference} (${scheme}:)`);
+      }
+    }
+
+    for (const [type, expectedPart, input] of [
+      ["leading", (scheme === "https" ? cpString : encodeURIComponent(cpString)) + "test", String.fromCodePoint(i) + "test"],
+      ["middle", "te" + (scheme === "https" ? cpString : encodeURIComponent(cpString)) + "st", "te" + String.fromCodePoint(i) + "st"],
+      ["trailing", "test" + (scheme === "https" ? cpString : encodeURIComponent(cpString)), "test" + String.fromCodePoint(i)]
+    ]) {
+      test(() => {
+        const expected = i === 0x00 ? "host" : stripped ? "test" : expectedPart;
+        const url = urlRecord(scheme);
+        url.host = input;
+        assert_equals(url.host, expected + ":8000", "property");
+        assert_equals(url.href, urlString({ scheme, host: expected }), "href");
+      }, `Setting host with ${type} ${cpReference} (${scheme}:)`);
+
+      test(() => {
+        const expected = i === 0x00 ? "host" : stripped ? "test" : expectedPart;
+        const url = urlRecord(scheme);
+        url.hostname = input;
+        assert_equals(url.hostname, expected, "property");
+        assert_equals(url.href, urlString({ scheme, host: expected }), "href");
+      }, `Setting hostname with ${type} ${cpReference} (${scheme}:)`);
+    }
+
+    test(() => {
+      const expected = stripped ? "9000" : "8000";
+      const url = urlRecord(scheme);
+      url.port = String.fromCodePoint(i) + "9000";
+      assert_equals(url.port, expected, "property");
+      assert_equals(url.href, urlString({ scheme, port: expected }), "href");
+    }, `Setting port with leading ${cpReference} (${scheme}:)`);
+
+    test(() => {
+      const expected = stripped ? "9000" : "90";
+      const url = urlRecord(scheme);
+      url.port = "90" + String.fromCodePoint(i) + "00";
+      assert_equals(url.port, expected, "property");
+      assert_equals(url.href, urlString({ scheme, port: expected }), "href");
+    }, `Setting port with middle ${cpReference} (${scheme}:)`);
+
+    test(() => {
+      const expected = "9000";
+      const url = urlRecord(scheme);
+      url.port = "9000" + String.fromCodePoint(i);
+      assert_equals(url.port, expected, "property");
+      assert_equals(url.href, urlString({ scheme, port: expected }), "href");
+    }, `Setting port with trailing ${cpReference} (${scheme}:)`);
+
+    for (const [property, separator] of [["pathname", "/"], ["search", "?"], ["hash", "#"]]) {
+      for (const [type, expectedPart, input] of [
+        ["leading", encodeURIComponent(cpString) + "test", String.fromCodePoint(i) + "test"],
+        ["middle", "te" + encodeURIComponent(cpString) + "st", "te" + String.fromCodePoint(i) + "st"],
+        ["trailing", "test" + encodeURIComponent(cpString), "test" + String.fromCodePoint(i)]
+      ]) {
+        test(() => {
+          const expected = stripped ? "test" : expectedPart;
+          const url = urlRecord(scheme);
+          url[property] = input;
+          assert_equals(url[property], separator + expected, "property");
+          assert_equals(url.href, urlString({ scheme, [property]: expected }), "href");
+        }, `Setting ${property} with ${type} ${cpReference} (${scheme}:)`);
+      }
+    }
+  }
+}
diff --git a/tests/wpt/web-platform-tests/wasm/serialization/module/nested-worker-success.any.js b/tests/wpt/web-platform-tests/wasm/serialization/module/nested-worker-success.any.js
index 5388ebcc39b..84fbd92a29c 100644
--- a/tests/wpt/web-platform-tests/wasm/serialization/module/nested-worker-success.any.js
+++ b/tests/wpt/web-platform-tests/wasm/serialization/module/nested-worker-success.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,dedicatedworker,sharedworker
+// META: global=dedicatedworker,sharedworker
 // META: script=resources/test-incrementer.js
 "use strict";
 
diff --git a/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/audioworkletnode-onerror.https.html b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/audioworkletnode-onerror.https.html
index ce39de54671..5bbb7304d97 100644
--- a/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/audioworkletnode-onerror.https.html
+++ b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/audioworkletnode-onerror.https.html
@@ -10,56 +10,51 @@
   </head>
   <body>
     <script id="layout-test-code">
-      let audit = Audit.createTaskRunner();
+      const audit = Audit.createTaskRunner();
 
-      setup(() => {
-        const sampleRate = 48000;
-        const renderLength = sampleRate * 0.1;
-        let context = new OfflineAudioContext(1, renderLength, sampleRate);
+      const filePath = 'processors/error-processor.js';
+      const sampleRate = 48000;
+      const renderLength = sampleRate * 0.1;
+      const context = new OfflineAudioContext(1, renderLength, sampleRate);
 
-        let filePath = 'processors/error-processor.js';
+      // Test |onprocessorerror| called upon failure of processor constructor.
+      audit.define('constructor-error', (task, should) => {
+        const constructorErrorWorkletNode =
+            new AudioWorkletNode(context, 'constructor-error');
+        constructorErrorWorkletNode.onprocessorerror = (error) => {
+          should(error instanceof ErrorEvent,
+                `onprocessorerror argument should be an ErrorEvent when
+                the constructor of AudioWorkletProcessor has an error.`)
+              .beTrue();
 
-        // Test |onprocessorerror| called upon failure of processor constructor.
-        audit.define('constructor-error',
-            (task, should) => {
-              let constructorErrorWorkletNode =
-                  new AudioWorkletNode(context, 'constructor-error');
-              constructorErrorWorkletNode.onprocessorerror = (e) => {
-                should(e instanceof ErrorEvent,
-                       `onprocessorerror argument should be an ErrorEvent when
-                        the constructor of AudioWorkletProcessor has
-                        an error.`).beTrue();
-                // Without 'processorerror' event callback, this test will be
-                // timed out.
-                task.done();
-              };
-            });
-
-        // Test |onprocessorerror| called upon failure of process() method.
-        audit.define('process-error',
-            (task, should) => {
-              let processErrorWorkletNode =
-                  new AudioWorkletNode(context, 'process-error');
-              processErrorWorkletNode.connect(context.destination);
-              processErrorWorkletNode.onprocessorerror = (e) => {
-                should(e instanceof ErrorEvent,
-                       `onprocessorerror argument should be an ErrorEvent when
-                        the process method of the AudioWorkletProcessor method
-                        has an error`).beTrue();
-                // Without 'processorerror' event callback, this test will be
-                // timed out.
-                task.done();
-              };
-
-              context.startRendering();
-            });
-
-        // 'error-processor.js' contains 2 class definitions represents an error
-        // in the constructor and an error in the process method respectively.
-        context.audioWorklet.addModule(filePath).then(() => {
-          audit.run();
-        });
+          // Without 'processorerror' event callback, this test will be
+          // timed out.
+          task.done();
+        };
       });
+
+      // Test |onprocessorerror| called upon failure of process() method.
+      audit.define('process-error', (task, should) => {
+        const processErrorWorkletNode =
+            new AudioWorkletNode(context, 'process-error');
+        processErrorWorkletNode.onprocessorerror = (error) => {
+          should(error instanceof ErrorEvent,
+                `onprocessorerror argument should be an ErrorEvent when
+                the process method of the AudioWorkletProcessor method
+                has an error.`)
+              .beTrue();
+
+          // Without 'processorerror' event callback, this test will be
+          // timed out.
+          task.done();
+        };
+
+        context.startRendering();
+      });
+
+      // 'error-processor.js' contains 2 class definitions represents an error
+      // in the constructor and an error in the process method respectively.
+      context.audioWorklet.addModule(filePath).then(() => audit.run());
     </script>
   </body>
 </html>
diff --git a/tests/wpt/web-platform-tests/webrtc/RTCPeerConnection-iceGatheringState.html b/tests/wpt/web-platform-tests/webrtc/RTCPeerConnection-iceGatheringState.html
index 13990c55435..4d514421006 100644
--- a/tests/wpt/web-platform-tests/webrtc/RTCPeerConnection-iceGatheringState.html
+++ b/tests/wpt/web-platform-tests/webrtc/RTCPeerConnection-iceGatheringState.html
@@ -84,6 +84,129 @@
       assert_unreached(`Unhandled rejection ${err.name}: ${err.message}`)));
   }, 'iceGatheringState should eventually become complete after setLocalDescription');
 
+  const iceGatheringStateTransitions = async (pc, ...states) => {
+    for (const state of states) {
+      await new Promise((resolve, reject) => {
+        pc.addEventListener('icegatheringstatechange', () => {
+          if (pc.iceGatheringState == state) {
+            resolve();
+          } else {
+            reject(`Unexpected gathering state: ${pc.iceGatheringState}, was expecting ${state}`);
+          }
+        }, {once: true});
+      });
+    }
+  };
+
+  const initialOfferAnswer = async (pc1, pc2, offerOptions) => {
+    await pc1.setLocalDescription(
+      await pc1.createOffer(offerOptions));
+    const pc1Transitions = iceGatheringStateTransitions(pc1, 'gathering', 'complete');
+    await pc2.setRemoteDescription(pc1.localDescription);
+    await pc2.setLocalDescription(await pc2.createAnswer());
+    const pc2Transitions = iceGatheringStateTransitions(pc2, 'gathering', 'complete');
+    await pc1.setRemoteDescription(pc2.localDescription);
+
+    await pc1Transitions;
+    await pc2Transitions;
+  };
+
+  const expectNoMoreGatheringStateChanges = async (t, pc) => {
+    pc.onicegatheringstatechange = t.step_func(() => assert_unreached('Should not get an icegatheringstatechange right now!'));
+  };
+
+  promise_test(async t => {
+    const pc1 = new RTCPeerConnection();
+    t.add_cleanup(() => pc1.close());
+    const pc2 = new RTCPeerConnection();
+    t.add_cleanup(() => pc2.close());
+    await initialOfferAnswer(pc1, pc2, {offerToReceiveAudio: true});
+
+    expectNoMoreGatheringStateChanges(t, pc1);
+    expectNoMoreGatheringStateChanges(t, pc2);
+
+    await pc1.setLocalDescription(await pc1.createOffer());
+    await pc2.setLocalDescription(await pc2.createOffer());
+
+    await new Promise(r => t.step_timeout(r, 500));
+  }, 'setLocalDescription(reoffer) with no new transports should not cause iceGatheringState to change');
+
+  promise_test(async t => {
+    const pc1 = new RTCPeerConnection();
+    t.add_cleanup(() => pc1.close());
+    const pc2 = new RTCPeerConnection();
+    t.add_cleanup(() => pc2.close());
+    await initialOfferAnswer(pc1, pc2, {offerToReceiveAudio: true});
+    await pc1.setLocalDescription(await pc1.createOffer({iceRestart: true}));
+    await iceGatheringStateTransitions(pc1, 'gathering', 'complete');
+    expectNoMoreGatheringStateChanges(t, pc1);
+    await pc1.setLocalDescription({type: 'rollback'});
+    await new Promise(r => t.step_timeout(r, 1000));
+  }, 'rolling back an ICE restart when gathering is complete should not result in iceGatheringState changes');
+
+  promise_test(async t => {
+    const pc1 = new RTCPeerConnection();
+    t.add_cleanup(() => pc1.close());
+    const pc2 = new RTCPeerConnection();
+    t.add_cleanup(() => pc2.close());
+    await initialOfferAnswer(pc1, pc2, {offerToReceiveAudio:true});
+    await pc1.setLocalDescription(await pc1.createOffer({iceRestart: true}));
+    await iceGatheringStateTransitions(pc1, 'gathering', 'complete');
+  }, 'setLocalDescription(reoffer) with a new transport should cause iceGatheringState to go to "checking" and then "complete"');
+
+  promise_test(async t => {
+    const pc1 = new RTCPeerConnection();
+    t.add_cleanup(() => pc1.close());
+    const pc2 = new RTCPeerConnection();
+    t.add_cleanup(() => pc2.close());
+    expectNoMoreGatheringStateChanges(t, pc2);
+    const offer = await pc1.createOffer({offerToReceiveAudio: true});
+    await pc2.setRemoteDescription(offer);
+    await pc2.setRemoteDescription(offer);
+    await pc2.setRemoteDescription({type: 'rollback'});
+    await pc2.setRemoteDescription(offer);
+  }, 'sRD does not cause ICE gathering state changes')
+
+  promise_test(async t => {
+    const pc = new RTCPeerConnection();
+    t.add_cleanup(() => pc.close());
+    await pc.setLocalDescription(
+      await pc.createOffer({offerToReceiveAudio: true}));
+    await iceGatheringStateTransitions(pc, 'gathering', 'complete');
+    await pc.setLocalDescription({type: 'rollback'});
+    await iceGatheringStateTransitions(pc, 'new');
+  }, 'setLocalDescription(rollback) of original offer should cause iceGatheringState to reach "new" when starting in "complete"');
+
+  promise_test(async t => {
+    const pc = new RTCPeerConnection();
+    t.add_cleanup(() => pc.close());
+    await pc.setLocalDescription(
+      await pc.createOffer({offerToReceiveAudio: true}));
+    await iceGatheringStateTransitions(pc, 'gathering');
+    await pc.setLocalDescription({type: 'rollback'});
+    // We might go directly to 'new', or we might go to 'complete' first,
+    // depending on timing. Allow either.
+    await Promise.any([
+      iceGatheringStateTransitions(pc, 'new'),
+      iceGatheringStateTransitions(pc, 'complete', 'new')]);
+  }, 'setLocalDescription(rollback) of original offer should cause iceGatheringState to reach "new" when starting in "gathering"');
+
+  promise_test(async t => {
+    const pc1 = new RTCPeerConnection();
+    t.add_cleanup(() => pc1.close());
+    const pc2 = new RTCPeerConnection();
+    t.add_cleanup(() => pc2.close());
+    await initialOfferAnswer(pc1, pc2, {offerToReceiveAudio: true});
+
+    pc1.getTransceivers()[0].stop();
+    await pc1.setLocalDescription(await pc1.createOffer());
+    await pc2.setRemoteDescription(pc1.localDescription);
+    await pc2.setLocalDescription(await pc2.createAnswer());
+    await iceGatheringStateTransitions(pc2, 'new');
+    await pc1.setRemoteDescription(pc2.localDescription);
+    await iceGatheringStateTransitions(pc1, 'new');
+  }, 'renegotiation that closes all transports should result in ICE gathering state "new"');
+
   /*
     4.4.2.  RTCIceGatheringState Enum
       gathering
diff --git a/tests/wpt/web-platform-tests/webxr/resources/webxr_util.js b/tests/wpt/web-platform-tests/webxr/resources/webxr_util.js
index 20585ef7379..fcee8930367 100644
--- a/tests/wpt/web-platform-tests/webxr/resources/webxr_util.js
+++ b/tests/wpt/web-platform-tests/webxr/resources/webxr_util.js
@@ -149,6 +149,7 @@ function forEachWebxrObject(callback) {
   callback(window.XRFrameRequestCallback, 'XRFrameRequestCallback');
   callback(window.XRPresentationContext, 'XRPresentationContext');
   callback(window.XRFrame, 'XRFrame');
+  callback(window.XRLayer, 'XRLayer');
   callback(window.XRView, 'XRView');
   callback(window.XRViewport, 'XRViewport');
   callback(window.XRViewerPose, 'XRViewerPose');
diff --git a/tests/wpt/web-platform-tests/workers/SharedWorker-MessageEvent-source.any.js b/tests/wpt/web-platform-tests/workers/SharedWorker-MessageEvent-source.any.js
index b3a60348494..faf48cf9386 100644
--- a/tests/wpt/web-platform-tests/workers/SharedWorker-MessageEvent-source.any.js
+++ b/tests/wpt/web-platform-tests/workers/SharedWorker-MessageEvent-source.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,sharedworker
+// META: global=sharedworker
 const t = async_test("Make sure that MessageEvent.source is properly set in connect event.");
 onconnect = t.step_func_done((event) => {
   assert_equals(event.__proto__, MessageEvent.prototype);
diff --git a/tests/wpt/web-platform-tests/workers/SharedWorker-replace-EventHandler.any.js b/tests/wpt/web-platform-tests/workers/SharedWorker-replace-EventHandler.any.js
index be9d71257a4..90c7d2d08d1 100644
--- a/tests/wpt/web-platform-tests/workers/SharedWorker-replace-EventHandler.any.js
+++ b/tests/wpt/web-platform-tests/workers/SharedWorker-replace-EventHandler.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,sharedworker
+// META: global=sharedworker
 // https://crbug.com/239669
 const t = async_test("Tests that repeatedly setting 'onerror' within a shared worker doesnt crash.");
 onconnect = t.step_func_done((event) => {
diff --git a/tests/wpt/web-platform-tests/workers/Worker-base64.any.js b/tests/wpt/web-platform-tests/workers/Worker-base64.any.js
index b5957f201f1..3aeab9045bb 100644
--- a/tests/wpt/web-platform-tests/workers/Worker-base64.any.js
+++ b/tests/wpt/web-platform-tests/workers/Worker-base64.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,worker
+// META: global=worker
 test(() => {
   assert_true(typeof atob === 'function');
   assert_true(typeof btoa === 'function');
diff --git a/tests/wpt/web-platform-tests/workers/Worker-constructor-proto.any.js b/tests/wpt/web-platform-tests/workers/Worker-constructor-proto.any.js
index f0544b6c15a..5a4a6aa1137 100644
--- a/tests/wpt/web-platform-tests/workers/Worker-constructor-proto.any.js
+++ b/tests/wpt/web-platform-tests/workers/Worker-constructor-proto.any.js
@@ -1,4 +1,4 @@
-//META: global=!default, worker
+//META: global=worker
 test(() => {
   const proto = {};
   assert_equals(String(Object.getPrototypeOf(WorkerLocation)).replace(/\n/g, " ").replace(/\s\s+/g, " "), "function () { [native code] }");
diff --git a/tests/wpt/web-platform-tests/workers/Worker-custom-event.any.js b/tests/wpt/web-platform-tests/workers/Worker-custom-event.any.js
index 201e0313b0e..d7e983aaddc 100644
--- a/tests/wpt/web-platform-tests/workers/Worker-custom-event.any.js
+++ b/tests/wpt/web-platform-tests/workers/Worker-custom-event.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,worker
+// META: global=worker
 async_test(t => {
   var target = self;
   target.addEventListener('custom-event', t.step_func_done());
diff --git a/tests/wpt/web-platform-tests/workers/Worker-formdata.any.js b/tests/wpt/web-platform-tests/workers/Worker-formdata.any.js
index 389d34b1c31..a07f194bd24 100644
--- a/tests/wpt/web-platform-tests/workers/Worker-formdata.any.js
+++ b/tests/wpt/web-platform-tests/workers/Worker-formdata.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,dedicatedworker
+// META: global=dedicatedworker
 test(() => {
   assert_own_property(self, 'FormData');
   assert_equals(FormData.length, 0);
diff --git a/tests/wpt/web-platform-tests/workers/Worker-location.sub.any.js b/tests/wpt/web-platform-tests/workers/Worker-location.sub.any.js
index 1c3dabff036..c05bb1750f7 100644
--- a/tests/wpt/web-platform-tests/workers/Worker-location.sub.any.js
+++ b/tests/wpt/web-platform-tests/workers/Worker-location.sub.any.js
@@ -1,4 +1,4 @@
-// META: global=!default, dedicatedworker, sharedworker
+// META: global=dedicatedworker,sharedworker
 test(() => {
   assert_equals(String(WorkerLocation).replace(/\n/g, " ").replace(/\s\s+/g, " "), "function WorkerLocation() { [native code] }");
   assert_true(location instanceof Object);
diff --git a/tests/wpt/web-platform-tests/workers/Worker-replace-event-handler.any.js b/tests/wpt/web-platform-tests/workers/Worker-replace-event-handler.any.js
index 1623573c7eb..ff7c764f2bd 100644
--- a/tests/wpt/web-platform-tests/workers/Worker-replace-event-handler.any.js
+++ b/tests/wpt/web-platform-tests/workers/Worker-replace-event-handler.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,worker
+// META: global=worker
 // This is a regression test for a crash bug in Chrome: http://crbug.com/239669
 function update() {
   onmessage = undefined;
diff --git a/tests/wpt/web-platform-tests/workers/Worker-replace-global-constructor.any.js b/tests/wpt/web-platform-tests/workers/Worker-replace-global-constructor.any.js
index f208f373636..d724c6c8ec6 100644
--- a/tests/wpt/web-platform-tests/workers/Worker-replace-global-constructor.any.js
+++ b/tests/wpt/web-platform-tests/workers/Worker-replace-global-constructor.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,worker
+// META: global=worker
 test(() => {
   try {
     self.MessageEvent = 'PASS';
diff --git a/tests/wpt/web-platform-tests/workers/Worker-replace-self.any.js b/tests/wpt/web-platform-tests/workers/Worker-replace-self.any.js
index 6e732c0730d..513fd4a257f 100644
--- a/tests/wpt/web-platform-tests/workers/Worker-replace-self.any.js
+++ b/tests/wpt/web-platform-tests/workers/Worker-replace-self.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,worker
+// META: global=worker
 test(() => {
   try {
     self = 'PASS';
diff --git a/tests/wpt/web-platform-tests/workers/WorkerNavigator-hardware-concurrency.any.js b/tests/wpt/web-platform-tests/workers/WorkerNavigator-hardware-concurrency.any.js
index bd4910fcafa..49db7503ffb 100644
--- a/tests/wpt/web-platform-tests/workers/WorkerNavigator-hardware-concurrency.any.js
+++ b/tests/wpt/web-platform-tests/workers/WorkerNavigator-hardware-concurrency.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,worker
+// META: global=worker
 test(() => {
   assert_true(navigator.hardwareConcurrency > 0);
 }, 'Test worker navigator hardware concurrency.');
diff --git a/tests/wpt/web-platform-tests/workers/WorkerNavigator.any.js b/tests/wpt/web-platform-tests/workers/WorkerNavigator.any.js
index 3588045c490..a9542af79aa 100644
--- a/tests/wpt/web-platform-tests/workers/WorkerNavigator.any.js
+++ b/tests/wpt/web-platform-tests/workers/WorkerNavigator.any.js
@@ -1,4 +1,4 @@
-// META: global=!default, worker
+// META: global=worker
 test(() => {
   assert_equals(typeof navigator, "object");
   assert_true(navigator instanceof WorkerNavigator);
diff --git a/tests/wpt/web-platform-tests/workers/examples/general.any.js b/tests/wpt/web-platform-tests/workers/examples/general.any.js
index 2aa82e3db90..8906350a7e8 100644
--- a/tests/wpt/web-platform-tests/workers/examples/general.any.js
+++ b/tests/wpt/web-platform-tests/workers/examples/general.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,worker
+// META: global=worker
 
 // See
 // https://web-platform-tests.org/writing-tests/testharness.html#multi-global-tests
diff --git a/tests/wpt/web-platform-tests/workers/examples/onconnect.any.js b/tests/wpt/web-platform-tests/workers/examples/onconnect.any.js
index 85546f2d11d..d43a9921833 100644
--- a/tests/wpt/web-platform-tests/workers/examples/onconnect.any.js
+++ b/tests/wpt/web-platform-tests/workers/examples/onconnect.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,sharedworker
+// META: global=sharedworker
 const t = async_test("onconnect is called");
 onconnect = t.step_func_done((event) => {
 });
diff --git a/tests/wpt/web-platform-tests/workers/importscripts_mime.any.js b/tests/wpt/web-platform-tests/workers/importscripts_mime.any.js
index d7e215853f4..950edb28d16 100644
--- a/tests/wpt/web-platform-tests/workers/importscripts_mime.any.js
+++ b/tests/wpt/web-platform-tests/workers/importscripts_mime.any.js
@@ -1,4 +1,4 @@
-// META: global=!window,worker
+// META: global=worker
 //
 // Tentative test for https://github.com/whatwg/html/issues/3255
 
diff --git a/tests/wpt/web-platform-tests/workers/interfaces/WorkerGlobalScope/location/returns-same-object.any.js b/tests/wpt/web-platform-tests/workers/interfaces/WorkerGlobalScope/location/returns-same-object.any.js
index ba9be9ce8a8..dd3560f040c 100644
--- a/tests/wpt/web-platform-tests/workers/interfaces/WorkerGlobalScope/location/returns-same-object.any.js
+++ b/tests/wpt/web-platform-tests/workers/interfaces/WorkerGlobalScope/location/returns-same-object.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,worker
+// META: global=worker
 
 test(function() {
   assert_equals(location, location);
diff --git a/tests/wpt/web-platform-tests/workers/interfaces/WorkerGlobalScope/self.any.js b/tests/wpt/web-platform-tests/workers/interfaces/WorkerGlobalScope/self.any.js
index a1aacc08808..64b4ee2faef 100644
--- a/tests/wpt/web-platform-tests/workers/interfaces/WorkerGlobalScope/self.any.js
+++ b/tests/wpt/web-platform-tests/workers/interfaces/WorkerGlobalScope/self.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,worker
+// META: global=worker
 
 test(function() {
   assert_equals(self, self);
diff --git a/tests/wpt/web-platform-tests/workers/postMessage_block.https.html b/tests/wpt/web-platform-tests/workers/postMessage_block.https.html
new file mode 100644
index 00000000000..c3e69f6193f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/workers/postMessage_block.https.html
@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body>
+<script>
+const t = async_test('postMessage and block');
+
+const w = new Worker('support/postMessage_block_worker.js');
+
+w.onmessage = t.step_func_done(() => {
+  const a = new Int32Array(new SharedArrayBuffer(4));
+  w.postMessage(a);
+  while (Atomics.load(a, 0) === 0);
+  assert_equals(Atomics.load(a, 0), 1);
+});
+</script>
+</body>
diff --git a/tests/wpt/web-platform-tests/workers/postMessage_block.https.html.headers b/tests/wpt/web-platform-tests/workers/postMessage_block.https.html.headers
new file mode 100644
index 00000000000..63b60e490f4
--- /dev/null
+++ b/tests/wpt/web-platform-tests/workers/postMessage_block.https.html.headers
@@ -0,0 +1,2 @@
+Cross-Origin-Opener-Policy: same-origin
+Cross-Origin-Embedder-Policy: require-corp
diff --git a/tests/wpt/web-platform-tests/workers/semantics/interface-objects/003.any.js b/tests/wpt/web-platform-tests/workers/semantics/interface-objects/003.any.js
index ea95deda298..b404f77321d 100644
--- a/tests/wpt/web-platform-tests/workers/semantics/interface-objects/003.any.js
+++ b/tests/wpt/web-platform-tests/workers/semantics/interface-objects/003.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,sharedworker
+// META: global=sharedworker
 
 var expected = [
   // https://html.spec.whatwg.org/
diff --git a/tests/wpt/web-platform-tests/workers/semantics/interface-objects/004.any.js b/tests/wpt/web-platform-tests/workers/semantics/interface-objects/004.any.js
index 358af74ca2c..65f59a0b377 100644
--- a/tests/wpt/web-platform-tests/workers/semantics/interface-objects/004.any.js
+++ b/tests/wpt/web-platform-tests/workers/semantics/interface-objects/004.any.js
@@ -1,4 +1,4 @@
-// META: global=!default,sharedworker
+// META: global=sharedworker
 
 var unexpected = [
   // https://html.spec.whatwg.org/
diff --git a/tests/wpt/web-platform-tests/workers/support/postMessage_block_worker.js b/tests/wpt/web-platform-tests/workers/support/postMessage_block_worker.js
new file mode 100644
index 00000000000..0c7bcacccaf
--- /dev/null
+++ b/tests/wpt/web-platform-tests/workers/support/postMessage_block_worker.js
@@ -0,0 +1,2 @@
+onmessage = e => Atomics.store(e.data, 0, 1);
+postMessage('ready');
diff --git a/tests/wpt/web-platform-tests/workers/support/postMessage_block_worker.js.headers b/tests/wpt/web-platform-tests/workers/support/postMessage_block_worker.js.headers
new file mode 100644
index 00000000000..6604450991a
--- /dev/null
+++ b/tests/wpt/web-platform-tests/workers/support/postMessage_block_worker.js.headers
@@ -0,0 +1 @@
+Cross-Origin-Embedder-Policy: require-corp