diff --git a/tests/wpt/metadata/MANIFEST.json b/tests/wpt/metadata/MANIFEST.json
index f7789ec1707..e8c7a0ebacf 100644
--- a/tests/wpt/metadata/MANIFEST.json
+++ b/tests/wpt/metadata/MANIFEST.json
@@ -373049,6 +373049,12 @@
      {}
     ]
    ],
+   "html/browsers/the-window-object/length-attribute.window.js": [
+    [
+     "/html/browsers/the-window-object/length-attribute.window.html",
+     {}
+    ]
+   ],
    "html/browsers/the-window-object/name-attribute.window.js": [
     [
      "/html/browsers/the-window-object/name-attribute.window.html",
@@ -625314,6 +625320,10 @@
    "653f12b4646c06ffa65f84cd2dfe72566f9662ff",
    "testharness"
   ],
+  "html/browsers/the-window-object/length-attribute.window.js": [
+   "d56e1e469280436e27d4a00d3e70f1d4773c80a7",
+   "testharness"
+  ],
   "html/browsers/the-window-object/name-attribute.window.js": [
    "f266dd7acb96cc473129c066e59f027c2eb067f0",
    "testharness"
diff --git a/tests/wpt/metadata/css/css-transitions/properties-value-inherit-001.html.ini b/tests/wpt/metadata/css/css-transitions/properties-value-inherit-001.html.ini
index 7f17425c4aa..5d20389c8e9 100644
--- a/tests/wpt/metadata/css/css-transitions/properties-value-inherit-001.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/properties-value-inherit-001.html.ini
@@ -56,6 +56,3 @@
   [background-position length(px) / events]
     expected: FAIL
 
-  [font-size length(em) / events]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/cssom-view/scroll-behavior-smooth.html.ini b/tests/wpt/metadata/css/cssom-view/scroll-behavior-smooth.html.ini
index ee754ce4aa3..bcd187f508c 100644
--- a/tests/wpt/metadata/css/cssom-view/scroll-behavior-smooth.html.ini
+++ b/tests/wpt/metadata/css/cssom-view/scroll-behavior-smooth.html.ini
@@ -3,9 +3,6 @@
   [scroll-behavior: smooth on DIV element]
     expected: FAIL
 
-  [Smooth scrolling while doing history navigation.]
-    expected: FAIL
-
   [Instant scrolling while doing history navigation.]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/encoding/single-byte-decoder.html.ini b/tests/wpt/metadata/encoding/single-byte-decoder.html.ini
index 9f65c319732..71d8e2b6761 100644
--- a/tests/wpt/metadata/encoding/single-byte-decoder.html.ini
+++ b/tests/wpt/metadata/encoding/single-byte-decoder.html.ini
@@ -58,7 +58,7 @@
     expected: FAIL
 
   [windows-1254: iso_8859-9:1989 (XMLHttpRequest)]
-    expected: TIMEOUT
+    expected: FAIL
 
   [windows-1258: cp1258 (XMLHttpRequest)]
     expected: TIMEOUT
@@ -99,9 +99,6 @@
   [windows-1255: x-cp1255 (XMLHttpRequest)]
     expected: TIMEOUT
 
-  [windows-1255: windows-1255 (XMLHttpRequest)]
-    expected: TIMEOUT
-
   [windows-1257: x-cp1257 (XMLHttpRequest)]
     expected: TIMEOUT
 
@@ -117,7 +114,16 @@
   [windows-1257: windows-1257 (XMLHttpRequest)]
     expected: TIMEOUT
 
-  [windows-1254: csisolatin5 (XMLHttpRequest)]
+  [windows-1254: iso88599 (XMLHttpRequest)]
+    expected: TIMEOUT
+
+  [windows-1254: iso-8859-9 (XMLHttpRequest)]
+    expected: TIMEOUT
+
+  [windows-1254: iso8859-9 (XMLHttpRequest)]
+    expected: TIMEOUT
+
+  [windows-1254: iso-ir-148 (XMLHttpRequest)]
     expected: TIMEOUT
 
 
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 d36a6a6fc70..18f786d4963 100644
--- a/tests/wpt/metadata/fetch/content-type/response.window.js.ini
+++ b/tests/wpt/metadata/fetch/content-type/response.window.js.ini
@@ -312,12 +312,3 @@
   [<iframe>: separate response Content-Type: text/plain */*;charset=gbk]
     expected: FAIL
 
-  [<iframe>: combined response Content-Type: text/html;" text/plain]
-    expected: FAIL
-
-  [<iframe>: combined response Content-Type: text/html */*]
-    expected: FAIL
-
-  [<iframe>: separate response Content-Type: */* text/html]
-    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 87c807a49ff..4d78243e885 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 +11,9 @@
   [X-Content-Type-Options%3A%20nosniff%0C]
     expected: FAIL
 
+  [X-Content-Type-Options%3A%20%22nosniFF%22]
+    expected: FAIL
+
+  [Content-Type-Options%3A%20nosniff]
+    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
new file mode 100644
index 00000000000..87b07c3e670
--- /dev/null
+++ b/tests/wpt/metadata/html/browsers/history/the-history-interface/traverse_the_history_1.html.ini
@@ -0,0 +1,4 @@
+[traverse_the_history_1.html]
+  [Multiple history traversals from the same task]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/html/browsers/the-window-object/length-attribute.window.js.ini b/tests/wpt/metadata/html/browsers/the-window-object/length-attribute.window.js.ini
new file mode 100644
index 00000000000..0fe80316f20
--- /dev/null
+++ b/tests/wpt/metadata/html/browsers/the-window-object/length-attribute.window.js.ini
@@ -0,0 +1,4 @@
+[length-attribute.window.html]
+  [Window object's length IDL attribute (and named access)]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/html/semantics/interactive-elements/the-details-element/toggleEvent.html.ini b/tests/wpt/metadata/html/semantics/interactive-elements/the-details-element/toggleEvent.html.ini
new file mode 100644
index 00000000000..9e522297c94
--- /dev/null
+++ b/tests/wpt/metadata/html/semantics/interactive-elements/the-details-element/toggleEvent.html.ini
@@ -0,0 +1,7 @@
+[toggleEvent.html]
+  [Calling open twice on 'details' fires only one toggle event]
+    expected: FAIL
+
+  [Setting open=true to opened 'details' element should not fire a toggle event at the 'details' element]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/bailout-exception-vs-return-xml.window.js.ini b/tests/wpt/metadata/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/bailout-exception-vs-return-xml.window.js.ini
index 25f0d603b3d..764409e0182 100644
--- a/tests/wpt/metadata/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/bailout-exception-vs-return-xml.window.js.ini
+++ b/tests/wpt/metadata/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/bailout-exception-vs-return-xml.window.js.ini
@@ -1,5 +1,5 @@
 [bailout-exception-vs-return-xml.window.html]
-  expected: TIMEOUT
+  expected: CRASH
   [document.open should throw an InvalidStateError with XML document even when the ignore-opens-during-unload counter is greater than 0 (during beforeunload event)]
     expected: TIMEOUT
 
diff --git a/tests/wpt/mozilla/meta/css/transition_calc_implicit.html.ini b/tests/wpt/mozilla/meta/css/transition_calc_implicit.html.ini
deleted file mode 100644
index dbea4f293ad..00000000000
--- a/tests/wpt/mozilla/meta/css/transition_calc_implicit.html.ini
+++ /dev/null
@@ -1,2 +0,0 @@
-[transition_calc_implicit.html]
-  expected: TIMEOUT
diff --git a/tests/wpt/web-platform-tests/html/browsers/the-window-object/length-attribute.window.js b/tests/wpt/web-platform-tests/html/browsers/the-window-object/length-attribute.window.js
new file mode 100644
index 00000000000..d56e1e46928
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/browsers/the-window-object/length-attribute.window.js
@@ -0,0 +1,24 @@
+async_test(t => {
+  const frame = document.createElement("iframe");
+  frame.srcdoc = "<iframe name=x srcdoc='<iframe name=z></iframe>'></iframe><iframe name=y></iframe>";
+  frame.onload = t.step_func_done(() => {
+    const frameW = frame.contentWindow;
+    assert_equals(frameW.length, 2);
+    assert_not_equals(frameW.x, undefined);
+    assert_not_equals(frameW.y, undefined);
+    assert_equals(frameW.z, undefined);
+    assert_equals(frameW.x, frameW[0]);
+    assert_equals(frameW.y, frameW[1]);
+    const xFrameW = frameW.x;
+    assert_equals(xFrameW.length, 1);
+    assert_not_equals(xFrameW.z, undefined);
+    assert_equals(xFrameW.z, xFrameW[0]);
+    frame.remove();
+    assert_equals(frameW.length, 0);
+    assert_equals(frameW.x, undefined);
+    assert_equals(frameW[0], undefined);
+    assert_equals(xFrameW.length, 0);
+    assert_equals(xFrameW.z, undefined);
+  });
+  document.body.append(frame);
+}, "Window object's length IDL attribute (and named access)");