diff --git a/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-002.html.ini b/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-002.html.ini
new file mode 100644
index 00000000000..f64b45fea6b
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-002.html.ini
@@ -0,0 +1,4 @@
+[hit-test-floats-002.html]
+  [Hit test float]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-003.html.ini b/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-003.html.ini
new file mode 100644
index 00000000000..f29da48a2a0
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-003.html.ini
@@ -0,0 +1,4 @@
+[hit-test-floats-003.html]
+  [Miss float below something else]
+    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
new file mode 100644
index 00000000000..4bfb0c2053a
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-004.html.ini
@@ -0,0 +1,4 @@
+[hit-test-floats-004.html]
+  [Miss float below something else]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/css/css-backgrounds/border-image-image-type-003.htm.ini b/tests/wpt/metadata-layout-2020/css/css-backgrounds/border-image-image-type-003.htm.ini
new file mode 100644
index 00000000000..9e95010571c
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/css/css-backgrounds/border-image-image-type-003.htm.ini
@@ -0,0 +1,2 @@
+[border-image-image-type-003.htm]
+  expected: FAIL
diff --git a/tests/wpt/metadata-layout-2020/css/css-transforms/transform-scale-hittest.html.ini b/tests/wpt/metadata-layout-2020/css/css-transforms/transform-scale-hittest.html.ini
index 4a1e8110f6f..f8e7e539aae 100644
--- a/tests/wpt/metadata-layout-2020/css/css-transforms/transform-scale-hittest.html.ini
+++ b/tests/wpt/metadata-layout-2020/css/css-transforms/transform-scale-hittest.html.ini
@@ -2,3 +2,6 @@
   [Hit test intersecting scaled box]
     expected: FAIL
 
+  [Hit test within unscaled box]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/css/cssom-view/elementFromPoint-001.html.ini b/tests/wpt/metadata-layout-2020/css/cssom-view/elementFromPoint-001.html.ini
deleted file mode 100644
index e38782d8c85..00000000000
--- a/tests/wpt/metadata-layout-2020/css/cssom-view/elementFromPoint-001.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[elementFromPoint-001.html]
-  [CSSOM View - 5 - extensions to the Document interface]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-layout-2020/css/cssom-view/elementsFromPoint-invalid-cases.html.ini b/tests/wpt/metadata-layout-2020/css/cssom-view/elementsFromPoint-invalid-cases.html.ini
deleted file mode 100644
index e181af5397f..00000000000
--- a/tests/wpt/metadata-layout-2020/css/cssom-view/elementsFromPoint-invalid-cases.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[elementsFromPoint-invalid-cases.html]
-  [The root element is the last element returned for otherwise empty queries within the viewport]
-    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 87d9db57cdc..ed14e0d493b 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
@@ -312,24 +312,24 @@
   [Response: combined response Content-Type: text/html;" \\" text/plain ";charset=GBK]
     expected: NOTRUN
 
-  [<iframe>: separate response Content-Type: text/html */*;charset=gbk]
-    expected: FAIL
-
-  [<iframe>: separate response Content-Type: text/html;" \\" text/plain]
-    expected: FAIL
-
-  [<iframe>: combined response Content-Type: text/html;x=" text/plain]
-    expected: FAIL
-
   [<iframe>: combined response Content-Type: text/html;charset=gbk text/plain text/html]
     expected: FAIL
 
   [<iframe>: separate response Content-Type: text/html;" text/plain]
     expected: FAIL
 
-  [<iframe>: separate response Content-Type: text/html */*]
-    expected: FAIL
-
   [<iframe>: separate response Content-Type: text/plain */*]
     expected: FAIL
 
+  [<iframe>: combined response Content-Type: text/html */*;charset=gbk]
+    expected: FAIL
+
+  [<iframe>: separate response Content-Type: text/html;x=" text/plain]
+    expected: FAIL
+
+  [<iframe>: combined response Content-Type: text/html;" \\" text/plain]
+    expected: FAIL
+
+  [<iframe>: separate response Content-Type: text/plain */*;charset=gbk]
+    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 258fe374697..b2ffc8abf78 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
@@ -56,6 +56,6 @@
   [separate text/javascript x/x]
     expected: FAIL
 
-  [separate text/javascript ]
+  [separate text/javascript error]
     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 fb0ce3ea7db..70efd28ddfc 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
@@ -11,9 +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
-
-  [X-Content-Type-Options%3A%0D%0AX-Content-Type-Options%3A%20nosniff]
+  [X-Content-Type-Options%3A%20no%0D%0AX-Content-Type-Options%3A%20nosniff]
     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
new file mode 100644
index 00000000000..87b07c3e670
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/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-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/browsers/windows/embedded-opener-remove-frame.html.ini b/tests/wpt/metadata-layout-2020/html/browsers/windows/embedded-opener-remove-frame.html.ini
index 8e2a63e3b7f..9a85a905394 100644
--- a/tests/wpt/metadata-layout-2020/html/browsers/windows/embedded-opener-remove-frame.html.ini
+++ b/tests/wpt/metadata-layout-2020/html/browsers/windows/embedded-opener-remove-frame.html.ini
@@ -1,5 +1,4 @@
 [embedded-opener-remove-frame.html]
-  expected: CRASH
   [opener of discarded nested browsing context]
     expected: FAIL
 
diff --git a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-2.html.ini b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-2.html.ini
index e63fe7c263e..c6f45be1eb2 100644
--- a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-2.html.ini
+++ b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-2.html.ini
@@ -1,5 +1,5 @@
 [iframe_sandbox_popups_escaping-2.html]
-  expected: CRASH
+  expected: TIMEOUT
   [Check that popups from a sandboxed iframe escape the sandbox if\n       allow-popups-to-escape-sandbox is used]
     expected: TIMEOUT
 
diff --git a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-3.html.ini b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-3.html.ini
index 338d283eb0e..295031c1812 100644
--- a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-3.html.ini
+++ b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-3.html.ini
@@ -1,4 +1,5 @@
 [iframe_sandbox_popups_escaping-3.html]
+  expected: TIMEOUT
   [Check that popups from a sandboxed iframe escape the sandbox if\n       allow-popups-to-escape-sandbox is used]
-    expected: FAIL
+    expected: TIMEOUT
 
diff --git a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-1.html.ini b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-1.html.ini
index 1b74d6e073d..0c89d5253df 100644
--- a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-1.html.ini
+++ b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-1.html.ini
@@ -1,4 +1,5 @@
 [iframe_sandbox_popups_nonescaping-1.html]
+  expected: CRASH
   [Check that popups from a sandboxed iframe do not escape the sandbox]
     expected: FAIL
 
diff --git a/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-img-element/list-of-available-images-matching.https.html.ini b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-img-element/list-of-available-images-matching.https.html.ini
new file mode 100644
index 00000000000..898a492d07a
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/html/semantics/embedded-content/the-img-element/list-of-available-images-matching.https.html.ini
@@ -0,0 +1,2 @@
+[list-of-available-images-matching.https.html]
+  expected: ERROR
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 450c88bd32b..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: FAIL
-
diff --git a/tests/wpt/metadata-layout-2020/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-process-zero-outputs.https.html.ini b/tests/wpt/metadata-layout-2020/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-process-zero-outputs.https.html.ini
new file mode 100644
index 00000000000..8b126147555
--- /dev/null
+++ b/tests/wpt/metadata-layout-2020/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-process-zero-outputs.https.html.ini
@@ -0,0 +1,4 @@
+[audioworkletprocessor-process-zero-outputs.https.html]
+  [Executing "check-zero-outputs"]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata-layout-2020/webmessaging/with-ports/017.html.ini b/tests/wpt/metadata-layout-2020/webmessaging/without-ports/017.html.ini
similarity index 100%
rename from tests/wpt/metadata-layout-2020/webmessaging/with-ports/017.html.ini
rename to tests/wpt/metadata-layout-2020/webmessaging/without-ports/017.html.ini
diff --git a/tests/wpt/metadata-layout-2020/workers/semantics/run-a-worker/003.html.ini b/tests/wpt/metadata-layout-2020/workers/semantics/run-a-worker/003.html.ini
index dd49aa8e457..c2c57aec558 100644
--- a/tests/wpt/metadata-layout-2020/workers/semantics/run-a-worker/003.html.ini
+++ b/tests/wpt/metadata-layout-2020/workers/semantics/run-a-worker/003.html.ini
@@ -1,5 +1,4 @@
 [003.html]
-  expected: ERROR
   [shared]
     expected: FAIL
 
diff --git a/tests/wpt/metadata-layout-2020/workers/shared-worker-in-data-url-context.window.js.ini b/tests/wpt/metadata-layout-2020/workers/shared-worker-in-data-url-context.window.js.ini
index 10dda3a6659..daa7a8c41bc 100644
--- a/tests/wpt/metadata-layout-2020/workers/shared-worker-in-data-url-context.window.js.ini
+++ b/tests/wpt/metadata-layout-2020/workers/shared-worker-in-data-url-context.window.js.ini
@@ -1,7 +1,8 @@
 [shared-worker-in-data-url-context.window.html]
+  expected: TIMEOUT
   [Create a shared worker in a data url frame]
     expected: FAIL
 
   [Create a data url shared worker in a data url frame]
-    expected: FAIL
+    expected: TIMEOUT
 
diff --git a/tests/wpt/metadata/MANIFEST.json b/tests/wpt/metadata/MANIFEST.json
index f3cd2301bc4..fb10b504cd7 100644
--- a/tests/wpt/metadata/MANIFEST.json
+++ b/tests/wpt/metadata/MANIFEST.json
@@ -260,6 +260,13 @@
      ]
     },
     "css-position": {
+     "nested-positions-crash.html": [
+      "dbc272fa093b154be09ea2843d01da50003aa690",
+      [
+       null,
+       {}
+      ]
+     ],
      "position-absolute-in-inline-crash.html": [
       "e7b2ef49c713d5ee081b7319d81c4c4b3ee15524",
       [
@@ -23986,6 +23993,81 @@
    }
   },
   "print-reftest": {
+   "css": {
+    "css-multicol": {
+     "column-balancing-paged-001-print.html": [
+      "cf8e343d0fff9c576ad88f00a4f68b310bf0e65d",
+      [
+       null,
+       [
+        [
+         "/css/css-multicol/column-balancing-paged-001-print-ref.html",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ]
+    }
+   },
+   "html": {
+    "rendering": {
+     "the-details-element": {
+      "details-page-break-after-1-print.html": [
+       "cb7fc466d09226fd7833a4d8066fb64fae755392",
+       [
+        null,
+        [
+         [
+          "/html/rendering/the-details-element/details-two-pages-print-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "details-page-break-after-2-print.html": [
+       "2f3d12bbe3b45b1495be4b658225de87898b4008",
+       [
+        null,
+        [
+         [
+          "/html/rendering/the-details-element/details-two-pages-print-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "details-page-break-before-1-print.html": [
+       "5abf4c39ae0644c49f99760b79a67173d9332d20",
+       [
+        null,
+        [
+         [
+          "/html/rendering/the-details-element/details-two-pages-print-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
+      "details-page-break-before-2-print.html": [
+       "2f3d12bbe3b45b1495be4b658225de87898b4008",
+       [
+        null,
+        [
+         [
+          "/html/rendering/the-details-element/details-two-pages-print-ref.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ]
+     }
+    }
+   },
    "infrastructure": {
     "reftest": {
      "reftest_match-print.html": [
@@ -122391,6 +122473,19 @@
        {}
       ]
      ],
+     "border-image-image-type-003.htm": [
+      "e59785df9292cf5a74f268d8a93dbada42b5db00",
+      [
+       null,
+       [
+        [
+         "/css/css-backgrounds/reference/border-image-image-type-003-ref.html",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
      "border-image-outset-003.html": [
       "27bc02682ca8d27a4f48997c3a8150438b33b86a",
       [
@@ -123539,6 +123634,71 @@
        {}
       ]
      ],
+     "break-at-end-container-edge-000.html": [
+      "4836f399de4fc8af657ff7729215ee7e89054798",
+      [
+       null,
+       [
+        [
+         "/css/reference/ref-filled-green-100px-square.xht",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
+     "break-at-end-container-edge-001.html": [
+      "d6d3374bc77bd4a920cb33273b9e38b5e80293f0",
+      [
+       null,
+       [
+        [
+         "/css/reference/ref-filled-green-100px-square.xht",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
+     "break-at-end-container-edge-002.html": [
+      "0002a558a1e0a2f5b9b53fb72f1045782f75bc0d",
+      [
+       null,
+       [
+        [
+         "/css/reference/ref-filled-green-100px-square.xht",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
+     "break-at-end-container-edge-003.html": [
+      "aafe3975ee0640532d624cfdd7b5d8feab34ab9a",
+      [
+       null,
+       [
+        [
+         "/css/reference/ref-filled-green-100px-square.xht",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
+     "break-at-end-container-edge-004.html": [
+      "c9d8b8fad5bf0ea4bb49fc65acc4a155dab62f25",
+      [
+       null,
+       [
+        [
+         "/css/reference/ref-filled-green-100px-square.xht",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
      "break-between-avoid-000.html": [
       "4816be7ae7d5d2a0bc2ea736d8af6b91027b134d",
       [
@@ -123851,6 +124011,45 @@
        {}
       ]
      ],
+     "tall-line-in-short-fragmentainer-000.html": [
+      "8e9515c4b6c0f85e8fe7635e207f2f67cb7283b9",
+      [
+       null,
+       [
+        [
+         "/css/reference/ref-filled-green-100px-square.xht",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
+     "tall-line-in-short-fragmentainer-001.html": [
+      "8f74878187a59dee3d060f14ee653264ae6e67f6",
+      [
+       null,
+       [
+        [
+         "/css/reference/ref-filled-green-100px-square.xht",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
+     "tall-line-in-short-fragmentainer-002.html": [
+      "ee277549633d08bdf6a36f124055b6cfc45afa5d",
+      [
+       null,
+       [
+        [
+         "/css/reference/ref-filled-green-100px-square.xht",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
      "trailing-child-margin-000.html": [
       "d204483a33ebff421cf9f3da9fab2d1183fcd1c0",
       [
@@ -162008,6 +162207,19 @@
        {}
       ]
      ],
+     "marker-text-combine-upright.html": [
+      "64b37a0c7d4355c560cdf02f078ddd65f252b2d9",
+      [
+       null,
+       [
+        [
+         "/css/css-pseudo/marker-text-combine-upright-ref.html",
+         "=="
+        ]
+       ],
+       {}
+      ]
+     ],
      "marker-unicode-bidi-default-ref.html": [
       "c3c6ee8a63d3959b8be77935532d23393ce8b5e0",
       [
@@ -168310,12 +168522,16 @@
        ]
       ],
       "hyphens-auto-010.html": [
-       "60ad082b8b43708c8c44b2263d081a5ed5c9a300",
+       "01acaf0c9bac7db58e032dd0154d2f9f6c127053",
        [
         null,
         [
          [
-          "/css/css-text/hyphens/reference/hyphens-auto-010-ref.html",
+          "/css/css-text/hyphens/reference/hyphens-auto-010M-ref.html",
+          "=="
+         ],
+         [
+          "/css/css-text/hyphens/reference/hyphens-auto-010H-ref.html",
           "=="
          ]
         ],
@@ -168464,12 +168680,12 @@
        ]
       ],
       "hyphens-none-012.html": [
-       "9c5c5d693c0ca88ad0713ffa897838860d731d88",
+       "5b70c95e4e1f43719a1c64fedacc3ca49190da02",
        [
         null,
         [
          [
-          "/css/css-text/hyphens/reference/hyphens-auto-010-ref.html",
+          "/css/css-text/hyphens/reference/hyphens-auto-010M-ref.html",
           "=="
          ]
         ],
@@ -168477,12 +168693,12 @@
        ]
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      ],
      "win-1252-xml.py": [
-      "09c32e4574b889974153abecb2b99eeb79c131fa",
+      "d88086e936ea17f75f30c18f4e9bd424ba609fff",
       []
      ],
      "workerxhr-origin-referrer.js": [
@@ -361629,7 +361901,7 @@
       []
      ],
      "zlib.py": [
-      "49ed69de79398828af12837e8d87ed8d1a3a7a3e",
+      "638813999ce07b8f6308f0dc5c0388ec82091069",
       []
      ]
     },
@@ -433024,6 +433296,15 @@
        {}
       ]
      ],
+     "element-request-fullscreen-options.tentative.html": [
+      "3646a6f0e9f6e9cbebdc94e41e3f768dddb2d08a",
+      [
+       null,
+       {
+        "testdriver": true
+       }
+      ]
+     ],
      "element-request-fullscreen.html": [
       "23b4d2f5bfbed1f84f0b51494bdc394fe56ebcb8",
       [
@@ -453420,7 +453701,7 @@
       ]
      ],
      "reporting-navigation.https.html": [
-      "2baf1755f0ca1ad2cc31dc0358a4c7b8014d41cd",
+      "7087985990e6823b0f7b1bcb22e57b25a753d605",
       [
        null,
        {
@@ -461569,6 +461850,13 @@
          {}
         ]
        ],
+       "list-of-available-images-matching.https.html": [
+        "4843d219156ddc92d3460cf04b7e8acfab7c8368",
+        [
+         null,
+         {}
+        ]
+       ],
        "move-element-and-scroll.html": [
         "3c95fae5bf354f68c20b9a2ce31f8c041dbee724",
         [
@@ -480210,7 +480498,28 @@
    },
    "origin-isolation": {
     "about-blank.https.sub.html": [
-     "ec24853a1605678102d7f025a386c82b44d9af9b",
+     "50a07ff0c02e45b4fb5cf5018d1b811f7944211d",
+     [
+      null,
+      {}
+     ]
+    ],
+    "getter-data-url.https.html": [
+     "da2c87b1270eb29e481997367c4f9b0643da1d2b",
+     [
+      null,
+      {}
+     ]
+    ],
+    "getter-removed-iframe.sub.https.html": [
+     "a1373468e22feab2332c547a91ad2c732440720e",
+     [
+      null,
+      {}
+     ]
+    ],
+    "getter-sandboxed-iframe.sub.https.html": [
+     "366fae6e5e959754bd6e38b4481cf26198cbe981",
      [
       null,
       {}
@@ -480224,140 +480533,140 @@
      ]
     ],
     "insecure-http.sub.html": [
-     "1e78b13385727e0cbb091b6469d1e7c9c0905093",
+     "83df16af4551339915c45325ce748bc166f7fe1b",
      [
       null,
       {}
      ]
     ],
     "parent-no-child-bad-subdomain.sub.https.html": [
-     "ae55f5d83e10ad6c5e0cda383fc02d8f8690a8bf",
+     "cfa39aaee034b0fe5e680e4f796a35d25a1e9a0a",
      [
       null,
       {}
      ]
     ],
     "parent-no-child-yes-same.sub.https.html": [
-     "8e32649d3a2d23cef359bedfae318bafbf3ca1c8",
+     "ece3b9732a5acbfaa22178404683999f8f0f9dc0",
      [
       null,
       {}
      ]
     ],
     "parent-no-child-yes-subdomain.sub.https.html": [
-     "7f4a9413e35702c0831f808bc64cc78cb2b6e1fe",
+     "ab060e24f4976ae90e37d9daa6012e2b668c0b2a",
      [
       null,
       {}
      ]
     ],
     "parent-no-child-yes-with-params-subdomain.sub.https.html": [
-     "0208ac3e14c66e61f1c49bcb20c31d7ab1faf50b",
+     "e1459b9cc08a92608ce7500fc06f6378e7894477",
      [
       null,
       {}
      ]
     ],
     "parent-no-child1-no-child2-yes-children-different.sub.https.html": [
-     "c019ef2fe7dfd026e59eff7a7a3e294d6601c576",
+     "17ee8a678a63a77c6010d882c2534304b950bbf3",
      [
       null,
       {}
      ]
     ],
     "parent-no-child1-no-child2-yes-children-same.sub.https.html": [
-     "9ca18f8941b37553d3797554d7e77d1260c1ce01",
+     "17b82bc09df5cbe5c10a25099a99f04a45128c38",
      [
       null,
       {}
      ]
     ],
     "parent-no-child1-yes-child2-no-children-same.sub.https.html": [
-     "2947e629bd51d71dfa179c04ae0dc32aaac00097",
+     "f6955c55c25a86e6b7c5024d39edb7a2ec3d4a12",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child-no-same.sub.https.html": [
-     "aa1dd94682ea817c0a7af881837d71da583517a1",
+     "7edebe9bd88d96be9552a2a514653a35940f1eac",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child-no-subdomain.sub.https.html": [
-     "5055d295d03711917378895392f44bbe783adc2b",
+     "f0cd3c481130cfd24f1de85aef332afe65a9703a",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child-yes-same.sub.https.html": [
-     "3d99486a3cb517763f68872a67217607f4c27777",
+     "c4917819617fc9f99a306c75b070299bab8f6302",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child-yes-subdomain.sub.https.html": [
-     "afc8f5b2acdf9eb8f0d92f2bb60df47fe379468b",
+     "fc5b19843cbe496a67ccb9d553d78af0d138ed83",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child1-no-child2-no-children-different.sub.https.html": [
-     "77a77d50a1c83f5e75731131c1d3133f8fba3dc3",
+     "1635bd63848a40956127073113b2c49801620263",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child1-no-child2-no-children-same.sub.https.html": [
-     "b3f18e8560f7f392f9128af291037013abbc9493",
+     "0f2f29025e762491d83bda27b5a2a1bc8262ff4f",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child1-no-child2-yes-children-different.sub.https.html": [
-     "8e7b4d3ee5c4b1c659c44327a5c34e008f60e871",
+     "c830e1548c073af129cd43e9591f19476461f91a",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child1-no-child2-yes-children-same.sub.https.html": [
-     "260ac80d2ff4ae91b144827790f49df71960224d",
+     "dc157a9eef9125fd9bd66171b1e10045a9ee0e7a",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child1-yes-child2-no-children-same.sub.https.html": [
-     "ae54fcd02ea8e16a576161d83d1fc4b5844e1c39",
+     "033fdd2827fddfcbf09411b9c6c1e9ab4bdaaca1",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child1-yes-child2-yes-children-different.sub.https.html": [
-     "775f753561b3864603796c1bbfb91976371cf040",
+     "2c1f1341df5187bdd294ef9727cb190265898c48",
      [
       null,
       {}
      ]
     ],
     "parent-yes-child1-yes-child2-yes-children-same.sub.https.html": [
-     "a3b0939862ce4d4043c45a607350f70e34f221fb",
+     "2de08307fcb79f843a20d48f8a78e974a61345b9",
      [
       null,
       {}
      ]
     ],
     "removing-iframes.sub.https.html": [
-     "2f01562b04cc83bc379088f5e660b130db44bfd1",
+     "3a6d91c447a97231257a226622f125426d174c72",
      [
       null,
       {}
@@ -517576,6 +517885,13 @@
         {}
        ]
       ],
+      "audioworkletprocessor-process-zero-outputs.https.html": [
+       "e1c19f0d759566f9d138eb2a05cc31e6d55575cf",
+       [
+        null,
+        {}
+       ]
+      ],
       "audioworkletprocessor-promises.https.html": [
        "8f83aac4baa1f40ff5a1cc3982855776d4a5b119",
        [
@@ -552170,13 +552486,6 @@
        {}
       ]
      ],
-     "border-image-image-type-003.htm": [
-      "b2710c15e8cf83b54142626468b5356f10749d01",
-      [
-       null,
-       {}
-      ]
-     ],
      "border-image-outset-001.htm": [
       "db0a8f5f6bb7ecfa034ae0d53f1833e26cc45fc3",
       [
diff --git a/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-002.html.ini b/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-002.html.ini
new file mode 100644
index 00000000000..f64b45fea6b
--- /dev/null
+++ b/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-002.html.ini
@@ -0,0 +1,4 @@
+[hit-test-floats-002.html]
+  [Hit test float]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-003.html.ini b/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-003.html.ini
new file mode 100644
index 00000000000..f29da48a2a0
--- /dev/null
+++ b/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-003.html.ini
@@ -0,0 +1,4 @@
+[hit-test-floats-003.html]
+  [Miss float below something else]
+    expected: FAIL
+
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
new file mode 100644
index 00000000000..4bfb0c2053a
--- /dev/null
+++ b/tests/wpt/metadata/css/CSS2/floats/hit-test-floats-004.html.ini
@@ -0,0 +1,4 @@
+[hit-test-floats-004.html]
+  [Miss float below something else]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/css-backgrounds/border-image-image-type-003.htm.ini b/tests/wpt/metadata/css/css-backgrounds/border-image-image-type-003.htm.ini
new file mode 100644
index 00000000000..9e95010571c
--- /dev/null
+++ b/tests/wpt/metadata/css/css-backgrounds/border-image-image-type-003.htm.ini
@@ -0,0 +1,2 @@
+[border-image-image-type-003.htm]
+  expected: FAIL
diff --git a/tests/wpt/metadata/css/css-transforms/transform-scale-hittest.html.ini b/tests/wpt/metadata/css/css-transforms/transform-scale-hittest.html.ini
index 4a1e8110f6f..f8e7e539aae 100644
--- a/tests/wpt/metadata/css/css-transforms/transform-scale-hittest.html.ini
+++ b/tests/wpt/metadata/css/css-transforms/transform-scale-hittest.html.ini
@@ -2,3 +2,6 @@
   [Hit test intersecting scaled box]
     expected: FAIL
 
+  [Hit test within unscaled box]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/cssom-view/elementFromPoint-001.html.ini b/tests/wpt/metadata/css/cssom-view/elementFromPoint-001.html.ini
deleted file mode 100644
index e38782d8c85..00000000000
--- a/tests/wpt/metadata/css/cssom-view/elementFromPoint-001.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[elementFromPoint-001.html]
-  [CSSOM View - 5 - extensions to the Document interface]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/cssom-view/elementsFromPoint-invalid-cases.html.ini b/tests/wpt/metadata/css/cssom-view/elementsFromPoint-invalid-cases.html.ini
deleted file mode 100644
index e181af5397f..00000000000
--- a/tests/wpt/metadata/css/cssom-view/elementsFromPoint-invalid-cases.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[elementsFromPoint-invalid-cases.html]
-  [The root element is the last element returned for otherwise empty queries within the viewport]
-    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 bcbdd9595a0..3da1de327d4 100644
--- a/tests/wpt/metadata/fetch/content-type/response.window.js.ini
+++ b/tests/wpt/metadata/fetch/content-type/response.window.js.ini
@@ -312,24 +312,24 @@
   [fetch(): separate response Content-Type: text/plain ]
     expected: NOTRUN
 
-  [<iframe>: separate response Content-Type: text/html */*;charset=gbk]
-    expected: FAIL
-
-  [<iframe>: separate response Content-Type: text/html;" \\" text/plain]
-    expected: FAIL
-
-  [<iframe>: combined response Content-Type: text/html;x=" text/plain]
-    expected: FAIL
-
   [<iframe>: combined response Content-Type: text/html;charset=gbk text/plain text/html]
     expected: FAIL
 
   [<iframe>: separate response Content-Type: text/html;" text/plain]
     expected: FAIL
 
-  [<iframe>: separate response Content-Type: text/html */*]
-    expected: FAIL
-
   [<iframe>: separate response Content-Type: text/plain */*]
     expected: FAIL
 
+  [<iframe>: combined response Content-Type: text/html */*;charset=gbk]
+    expected: FAIL
+
+  [<iframe>: separate response Content-Type: text/html;x=" text/plain]
+    expected: FAIL
+
+  [<iframe>: combined response Content-Type: text/html;" \\" text/plain]
+    expected: FAIL
+
+  [<iframe>: separate response Content-Type: text/plain */*;charset=gbk]
+    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 258fe374697..b2ffc8abf78 100644
--- a/tests/wpt/metadata/fetch/content-type/script.window.js.ini
+++ b/tests/wpt/metadata/fetch/content-type/script.window.js.ini
@@ -56,6 +56,6 @@
   [separate text/javascript x/x]
     expected: FAIL
 
-  [separate text/javascript ]
+  [separate text/javascript error]
     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 fb0ce3ea7db..70efd28ddfc 100644
--- a/tests/wpt/metadata/fetch/nosniff/parsing-nosniff.window.js.ini
+++ b/tests/wpt/metadata/fetch/nosniff/parsing-nosniff.window.js.ini
@@ -11,9 +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
-
-  [X-Content-Type-Options%3A%0D%0AX-Content-Type-Options%3A%20nosniff]
+  [X-Content-Type-Options%3A%20no%0D%0AX-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/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/browsers/windows/embedded-opener-remove-frame.html.ini b/tests/wpt/metadata/html/browsers/windows/embedded-opener-remove-frame.html.ini
index 2532dceabac..442db3cb549 100644
--- a/tests/wpt/metadata/html/browsers/windows/embedded-opener-remove-frame.html.ini
+++ b/tests/wpt/metadata/html/browsers/windows/embedded-opener-remove-frame.html.ini
@@ -1,5 +1,4 @@
 [embedded-opener-remove-frame.html]
-  expected: CRASH
   [opener and "removed" embedded documents]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-2.html.ini b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-2.html.ini
index e63fe7c263e..c6f45be1eb2 100644
--- a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-2.html.ini
+++ b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-2.html.ini
@@ -1,5 +1,5 @@
 [iframe_sandbox_popups_escaping-2.html]
-  expected: CRASH
+  expected: TIMEOUT
   [Check that popups from a sandboxed iframe escape the sandbox if\n       allow-popups-to-escape-sandbox is used]
     expected: TIMEOUT
 
diff --git a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-3.html.ini b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-3.html.ini
index f6a7aca3306..5f60c78e73c 100644
--- a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-3.html.ini
+++ b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_escaping-3.html.ini
@@ -1,5 +1,6 @@
 [iframe_sandbox_popups_escaping-3.html]
   type: testharness
+  expected: TIMEOUT
   [Check that popups from a sandboxed iframe escape the sandbox if\n       allow-popups-to-escape-sandbox is used]
-    expected: FAIL
+    expected: TIMEOUT
 
diff --git a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-1.html.ini b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-1.html.ini
index 3f7e3e9544f..4bc0524f105 100644
--- a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-1.html.ini
+++ b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-1.html.ini
@@ -1,5 +1,6 @@
 [iframe_sandbox_popups_nonescaping-1.html]
   type: testharness
+  expected: CRASH
   [Check that popups from a sandboxed iframe do not escape the sandbox]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/html/semantics/embedded-content/the-img-element/list-of-available-images-matching.https.html.ini b/tests/wpt/metadata/html/semantics/embedded-content/the-img-element/list-of-available-images-matching.https.html.ini
new file mode 100644
index 00000000000..898a492d07a
--- /dev/null
+++ b/tests/wpt/metadata/html/semantics/embedded-content/the-img-element/list-of-available-images-matching.https.html.ini
@@ -0,0 +1,2 @@
+[list-of-available-images-matching.https.html]
+  expected: ERROR
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 01f7b72cbe7..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: FAIL
-
diff --git a/tests/wpt/metadata/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-process-zero-outputs.https.html.ini b/tests/wpt/metadata/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-process-zero-outputs.https.html.ini
new file mode 100644
index 00000000000..8b126147555
--- /dev/null
+++ b/tests/wpt/metadata/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-process-zero-outputs.https.html.ini
@@ -0,0 +1,4 @@
+[audioworkletprocessor-process-zero-outputs.https.html]
+  [Executing "check-zero-outputs"]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/webmessaging/with-ports/017.html.ini b/tests/wpt/metadata/webmessaging/without-ports/017.html.ini
similarity index 100%
rename from tests/wpt/metadata/webmessaging/with-ports/017.html.ini
rename to tests/wpt/metadata/webmessaging/without-ports/017.html.ini
diff --git a/tests/wpt/metadata/workers/semantics/run-a-worker/003.html.ini b/tests/wpt/metadata/workers/semantics/run-a-worker/003.html.ini
index 49f489d2a1c..d6e39444229 100644
--- a/tests/wpt/metadata/workers/semantics/run-a-worker/003.html.ini
+++ b/tests/wpt/metadata/workers/semantics/run-a-worker/003.html.ini
@@ -1,6 +1,5 @@
 [003.html]
   type: testharness
-  expected: ERROR
   [shared]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/workers/shared-worker-in-data-url-context.window.js.ini b/tests/wpt/metadata/workers/shared-worker-in-data-url-context.window.js.ini
index 10dda3a6659..daa7a8c41bc 100644
--- a/tests/wpt/metadata/workers/shared-worker-in-data-url-context.window.js.ini
+++ b/tests/wpt/metadata/workers/shared-worker-in-data-url-context.window.js.ini
@@ -1,7 +1,8 @@
 [shared-worker-in-data-url-context.window.html]
+  expected: TIMEOUT
   [Create a shared worker in a data url frame]
     expected: FAIL
 
   [Create a data url shared worker in a data url frame]
-    expected: FAIL
+    expected: TIMEOUT
 
diff --git a/tests/wpt/web-platform-tests/background-fetch/resources/upload.py b/tests/wpt/web-platform-tests/background-fetch/resources/upload.py
index 585144efa6b..4c421c7d37b 100644
--- a/tests/wpt/web-platform-tests/background-fetch/resources/upload.py
+++ b/tests/wpt/web-platform-tests/background-fetch/resources/upload.py
@@ -1,3 +1,3 @@
 # Simply returns the request body to check if the upload succeeded.
 def main(request, response):
-    return 200, [("Content-Type", request.headers['content-type'])], request.body
+    return 200, [(b"Content-Type", request.headers[b'content-type'])], request.body
diff --git a/tests/wpt/web-platform-tests/content-dpr/resources/dpr.py b/tests/wpt/web-platform-tests/content-dpr/resources/dpr.py
index 14d7d550fe2..969ac2458d8 100644
--- a/tests/wpt/web-platform-tests/content-dpr/resources/dpr.py
+++ b/tests/wpt/web-platform-tests/content-dpr/resources/dpr.py
@@ -1,24 +1,26 @@
+from wptserve.utils import isomorphic_decode
+
 def main(request, response):
     """
     Simple handler that sets a response header based on which client hint
     request headers were received.
     """
 
-    response.headers.append("Access-Control-Allow-Origin", "*")
+    response.headers.append(b"Access-Control-Allow-Origin", b"*")
     values = request.GET
-    name = values.first('name')
-    type = values.first('mimeType')
-    dpr = values.first('dpr')
+    name = values.first(b'name')
+    type = values.first(b'mimeType')
+    dpr = values.first(b'dpr')
     double = None
-    if 'double' in values:
-        double = values.first('double')
-    image_path = request.doc_root + "/".join(request.url_parts[2].split("/")[:-1]) + "/" + name
+    if b'double' in values:
+        double = values.first(b'double')
+    image_path = request.doc_root + u"/".join(request.url_parts[2].split(u"/")[:-1]) + u"/" + isomorphic_decode(name)
     f = open(image_path, "rb")
     buff = f.read()
     f.close()
-    response.headers.set("Content-Type", type)
-    response.headers.set("Content-DPR", dpr)
+    response.headers.set(b"Content-Type", type)
+    response.headers.set(b"Content-DPR", dpr)
     if double:
-        response.headers.append("Content-DPR", double)
-    response.headers.set("Content-Length", len(buff))
+        response.headers.append(b"Content-DPR", double)
+    response.headers.set(b"Content-Length", len(buff))
     response.content = buff
diff --git a/tests/wpt/web-platform-tests/cookies/http-state/resources/cookie-setter.py b/tests/wpt/web-platform-tests/cookies/http-state/resources/cookie-setter.py
index 758b1429f72..4ea366daa6e 100644
--- a/tests/wpt/web-platform-tests/cookies/http-state/resources/cookie-setter.py
+++ b/tests/wpt/web-platform-tests/cookies/http-state/resources/cookie-setter.py
@@ -1,6 +1,8 @@
 from os import path
 from os import listdir
 
+from wptserve.utils import isomorphic_decode
+
 """
 The main purpose of this script is to set cookies based on files in this folder:
     cookies/http-state/resources
@@ -13,18 +15,18 @@ If you want to run a test in isolation, append "?debug=" and the test id to the
 URL above.
 """
 
-SETUP_FILE_TEMPLATE = "{}-test"
-EXPECTATION_FILE_TEMPLATE = "{}-expected"
-EXPECTATION_HTML_SCAFFOLD = "iframe-expectation-doc.html.py-str"
-DEBUGGING_HTML_SCAFFOLD = "debugging-single-test.html.py-str"
-DEFAULT_RESOURCE_DIR = path.join("cookies", "http-state", "resources")
-DEFAULT_TEST_DIR = "test-files"
-ALL_TESTS = "all-tests.html.py-str"
+SETUP_FILE_TEMPLATE = u"{}-test"
+EXPECTATION_FILE_TEMPLATE = u"{}-expected"
+EXPECTATION_HTML_SCAFFOLD = u"iframe-expectation-doc.html.py-str"
+DEBUGGING_HTML_SCAFFOLD = u"debugging-single-test.html.py-str"
+DEFAULT_RESOURCE_DIR = path.join(u"cookies", u"http-state", u"resources")
+DEFAULT_TEST_DIR = u"test-files"
+ALL_TESTS = u"all-tests.html.py-str"
 
 
 def dump_file(directory, filename):
   """Reads a file into a string."""
-  return open(path.join(directory, filename), "r").read()
+  return open(path.join(directory, filename), u"r").read()
 
 
 class CookieTestResponse(object):
@@ -46,17 +48,17 @@ class CookieTestResponse(object):
     """Returns a full HTML document which contains the expectation."""
     html_frame = dump_file(self.__resources_dir, EXPECTATION_HTML_SCAFFOLD)
     expected_data = dump_file(self.__test_files_dir, self.__expectation_file)
-    return html_frame.format(**{'data' : expected_data})
+    return html_frame.format(**{u'data' : expected_data})
 
 def find_all_test_files(root):
   """Retrieves all files from the test-files/ folder and returns them as
   string pair as used in the JavaScript object. Sorted by filename."""
   all_files = []
-  line_template = '{{file: "{filename}", name: "{filename}"}},'
+  line_template = u'{{file: "{filename}", name: "{filename}"}},'
   for file in listdir(path.join(root, DEFAULT_RESOURCE_DIR, DEFAULT_TEST_DIR)):
-    if file.endswith('-test'):
-      name = file.replace('-test', '')
-      all_files.append(line_template.format(**{'filename' : name}))
+    if file.endswith(u'-test'):
+      name = file.replace(u'-test', u'')
+      all_files.append(line_template.format(**{u'filename' : name}))
   all_files.sort()
   return all_files
 
@@ -64,29 +66,29 @@ def generate_for_all_tests(root):
   """Returns an HTML document which loads and executes all tests in the
   test-files/ directory."""
   html_frame = dump_file(path.join(root, DEFAULT_RESOURCE_DIR), ALL_TESTS)
-  return html_frame % '\n'.join(find_all_test_files(root))
+  return html_frame % u'\n'.join(find_all_test_files(root))
 
 def main(request, response):
-  if "debug" in request.GET:
+  if b"debug" in request.GET:
     """If '?debug=' is set, return the document for a single test."""
     response.writer.write_status(200)
     response.writer.end_headers()
     html_frame = dump_file(path.join(request.doc_root, DEFAULT_RESOURCE_DIR),
                            DEBUGGING_HTML_SCAFFOLD)
-    test_file = html_frame % (request.GET['debug'])
+    test_file = html_frame % (isomorphic_decode(request.GET[b'debug']))
     response.writer.write_content(test_file)
-    return;
+    return
 
-  if "file" in request.GET:
+  if b"file" in request.GET:
     """If '?file=' is set, send a cookie and a document which contains the
     expectation of which cookies should be set by the browser in response."""
-    cookie_response = CookieTestResponse(request.GET['file'], request.doc_root)
+    cookie_response = CookieTestResponse(isomorphic_decode(request.GET[b'file']), request.doc_root)
 
     response.writer.write_status(200)
     response.writer.write(cookie_response.cookie_setting_header())
     response.writer.end_headers()
     response.writer.write_content(cookie_response.body_with_expectation())
-    return;
+    return
 
   """Without any arguments, return documentation and run all available tests."""
   response.writer.write_status(200)
diff --git a/tests/wpt/web-platform-tests/cookies/resources/drop.py b/tests/wpt/web-platform-tests/cookies/resources/drop.py
index 7491dad2fb5..ff405e95037 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/drop.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/drop.py
@@ -5,11 +5,10 @@ def main(request, response):
     headers = setNoCacheAndCORSHeaders(request, response)
     try:
         # Expire the named cookie, and return a JSON-encoded success code.
-        name = readParameter(request, paramName="name", requireValue=True)
+        name = readParameter(request, paramName=u"name", requireValue=True)
         scheme = request.url_parts.scheme
-        headers.append(makeDropCookie(name,  "https" == scheme))
-        return headers, '{"success": true}'
+        headers.append(makeDropCookie(name, u"https" == scheme))
+        return headers, b'{"success": true}'
     except:
-        return 500, headers, '{"error" : "Empty or missing name parameter."}'
-
+        return 500, headers, b'{"error" : "Empty or missing name parameter."}'
 
diff --git a/tests/wpt/web-platform-tests/cookies/resources/dropSameSite.py b/tests/wpt/web-platform-tests/cookies/resources/dropSameSite.py
index 4a3f890cb91..925c5e97699 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/dropSameSite.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/dropSameSite.py
@@ -6,8 +6,8 @@ def main(request, response):
     headers = setNoCacheAndCORSHeaders(request, response)
 
     # Expire the cookies, and return a JSON-encoded success code.
-    headers.append(makeDropCookie("samesite_strict", False))
-    headers.append(makeDropCookie("samesite_lax", False))
-    headers.append(makeDropCookie("samesite_none", False))
-    headers.append(makeDropCookie("samesite_unspecified", False))
-    return headers, '{"success": true}'
+    headers.append(makeDropCookie(b"samesite_strict", False))
+    headers.append(makeDropCookie(b"samesite_lax", False))
+    headers.append(makeDropCookie(b"samesite_none", False))
+    headers.append(makeDropCookie(b"samesite_unspecified", False))
+    return headers, b'{"success": true}'
diff --git a/tests/wpt/web-platform-tests/cookies/resources/dropSameSiteNone.py b/tests/wpt/web-platform-tests/cookies/resources/dropSameSiteNone.py
index 92d6105afb5..7c4f49ee9ac 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/dropSameSiteNone.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/dropSameSiteNone.py
@@ -6,6 +6,6 @@ def main(request, response):
     headers = setNoCacheAndCORSHeaders(request, response)
 
     # Expire the cookies, and return a JSON-encoded success code.
-    headers.append(makeDropCookie("samesite_none_insecure", False))
-    headers.append(makeDropCookie("samesite_none_secure", True))
-    return headers, '{"success": true}'
+    headers.append(makeDropCookie(b"samesite_none_insecure", False))
+    headers.append(makeDropCookie(b"samesite_none_secure", True))
+    return headers, b'{"success": true}'
diff --git a/tests/wpt/web-platform-tests/cookies/resources/dropSecure.py b/tests/wpt/web-platform-tests/cookies/resources/dropSecure.py
index f95e9a9b604..9820295697d 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/dropSecure.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/dropSecure.py
@@ -1,4 +1,4 @@
-from helpers import makeDropCookie, readParameter, setNoCacheAndCORSHeaders
+from helpers import makeDropCookie, setNoCacheAndCORSHeaders
 
 def main(request, response):
     """Respond to `/cookie/drop/secure` by dropping the two cookie set by
@@ -6,6 +6,6 @@ def main(request, response):
     headers = setNoCacheAndCORSHeaders(request, response)
 
     # Expire the cookies, and return a JSON-encoded success code.
-    headers.append(makeDropCookie("alone_secure", False))
-    headers.append(makeDropCookie("alone_insecure", False))
-    return headers, '{"success": true}'
+    headers.append(makeDropCookie(b"alone_secure", False))
+    headers.append(makeDropCookie(b"alone_insecure", False))
+    return headers, b'{"success": true}'
diff --git a/tests/wpt/web-platform-tests/cookies/resources/echo-json.py b/tests/wpt/web-platform-tests/cookies/resources/echo-json.py
index 8f82aa1e96c..9f1568e8166 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/echo-json.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/echo-json.py
@@ -1,15 +1,15 @@
-import json
+from wptserve.utils import isomorphic_decode
 
 def main(request, response):
-    headers = [("Content-Type", "application/json"),
-               ("Access-Control-Allow-Credentials", "true")]
+    headers = [(b"Content-Type", b"application/json"),
+               (b"Access-Control-Allow-Credentials", b"true")]
 
-    if "origin" in request.headers:
-        headers.append(("Access-Control-Allow-Origin", request.headers["origin"]))
+    if b"origin" in request.headers:
+        headers.append((b"Access-Control-Allow-Origin", request.headers[b"origin"]))
 
     values = []
     for key in request.cookies:
         for value in request.cookies.get_list(key):
-            values.append("\"%s\": \"%s\"" % (key, value))
-    body = "{ %s }" % ",".join(values)
+            values.append(u"\"%s\": \"%s\"" % (isomorphic_decode(key), value))
+    body = u"{ %s }" % u",".join(values)
     return headers, body
diff --git a/tests/wpt/web-platform-tests/cookies/resources/helpers.py b/tests/wpt/web-platform-tests/cookies/resources/helpers.py
index 145f2fea1a1..1002b84a8f9 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/helpers.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/helpers.py
@@ -1,47 +1,54 @@
-import urlparse
+from six import integer_types
+
+from six.moves.urllib.parse import parse_qs
+
+from wptserve.utils import isomorphic_encode
 
 def setNoCacheAndCORSHeaders(request, response):
     """Set Cache-Control, CORS and Content-Type headers appropriate for the cookie tests."""
-    headers = [("Content-Type", "application/json"),
-               ("Access-Control-Allow-Credentials", "true")]
+    headers = [(b"Content-Type", b"application/json"),
+               (b"Access-Control-Allow-Credentials", b"true")]
 
-    origin = "*"
-    if "origin" in request.headers:
-        origin = request.headers["origin"]
+    origin = b"*"
+    if b"origin" in request.headers:
+        origin = request.headers[b"origin"]
 
-    headers.append(("Access-Control-Allow-Origin", origin))
+    headers.append((b"Access-Control-Allow-Origin", origin))
     #headers.append(("Access-Control-Allow-Credentials", "true"))
-    headers.append(("Cache-Control", "no-cache"))
-    headers.append(("Expires", "Fri, 01 Jan 1990 00:00:00 GMT"))
+    headers.append((b"Cache-Control", b"no-cache"))
+    headers.append((b"Expires", b"Fri, 01 Jan 1990 00:00:00 GMT"))
 
     return headers
 
 def makeCookieHeader(name, value, otherAttrs):
     """Make a Set-Cookie header for a cookie with the name, value and attributes provided."""
     def makeAV(a, v):
-        if None == v or "" == v:
+        if None == v or b"" == v:
             return a
-        return "%s=%s" % (a, v)
+        if isinstance(v, integer_types):
+            return b"%s=%i" % (a, v)
+        else:
+            return b"%s=%s" % (a, v)
 
     # ensure cookie name is always first
-    attrs = ["%s=%s" % (name, value)]
-    attrs.extend(makeAV(a, v) for (a,v) in otherAttrs.iteritems())
-    return ("Set-Cookie", "; ".join(attrs))
+    attrs = [b"%s=%s" % (name, value)]
+    attrs.extend(makeAV(a, v) for (a, v) in otherAttrs.items())
+    return (b"Set-Cookie", b"; ".join((attrs)))
 
 def makeDropCookie(name, secure):
-    attrs = {"MaxAge": 0, "path": "/"}
+    attrs = {b"MaxAge": 0, b"path": b"/"}
     if secure:
-        attrs["secure"] = ""
-    return makeCookieHeader(name, "", attrs)
+        attrs[b"secure"] = b""
+    return makeCookieHeader(name, b"", attrs)
 
 def readParameter(request, paramName, requireValue):
     """Read a parameter from the request. Raise if requireValue is set and the
     parameter has an empty value or is not present."""
-    params = urlparse.parse_qs(request.url_parts.query)
+    params = parse_qs(request.url_parts.query)
     param = params[paramName][0].strip()
     if len(param) == 0:
-        raise Exception("Empty or missing name parameter.")
-    return param
+        raise Exception(u"Empty or missing name parameter.")
+    return isomorphic_encode(param)
 
 def readCookies(request):
     """Read the cookies from the client present in the request."""
@@ -52,4 +59,3 @@ def readCookies(request):
             # need to modify the test to take cookie names and value lists?
             cookies[key] = cookie.value
     return cookies
-
diff --git a/tests/wpt/web-platform-tests/cookies/resources/imgIfMatch.py b/tests/wpt/web-platform-tests/cookies/resources/imgIfMatch.py
index 08664415e6a..124cea4776e 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/imgIfMatch.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/imgIfMatch.py
@@ -4,13 +4,13 @@ def main(request, response):
     """Respond to `/cookie/imgIfMatch?name={name}&value={value}` with a 404 if
        the cookie isn't present, and a transparent GIF otherwise."""
     headers = helpers.setNoCacheAndCORSHeaders(request, response)
-    name = helpers.readParameter(request, paramName="name", requireValue=True)
-    value = helpers.readParameter(request, paramName="value", requireValue=True)
+    name = helpers.readParameter(request, paramName=u"name", requireValue=True)
+    value = helpers.readParameter(request, paramName=u"value", requireValue=True)
     cookiesWithMatchingNames = request.cookies.get_list(name)
     for cookie in cookiesWithMatchingNames:
         if cookie.value == value:
             # From https://github.com/mathiasbynens/small/blob/master/gif-transparent.gif
-            headers.append(("Content-Type","image/gif"))
-            gif = "\x47\x49\x46\x38\x39\x61\x01\x00\x01\x00\x80\x00\x00\xFF\xFF\xFF\x00\x00\x00\x21\xF9\x04\x01\x00\x00\x00\x00\x2C\x00\x00\x00\x00\x01\x00\x01\x00\x00\x02\x02\x44\x01\x00\x3B"
+            headers.append((b"Content-Type", b"image/gif"))
+            gif = b"\x47\x49\x46\x38\x39\x61\x01\x00\x01\x00\x80\x00\x00\xFF\xFF\xFF\x00\x00\x00\x21\xF9\x04\x01\x00\x00\x00\x00\x2C\x00\x00\x00\x00\x01\x00\x01\x00\x00\x02\x02\x44\x01\x00\x3B"
             return headers, gif
-    return 500, headers, '{"error": {"message": "The cookie\'s value did not match the given value."}}'
+    return 500, headers, b'{"error": {"message": "The cookie\'s value did not match the given value."}}'
diff --git a/tests/wpt/web-platform-tests/cookies/resources/list.py b/tests/wpt/web-platform-tests/cookies/resources/list.py
index 3fe7dd6ae0d..a54d2acd003 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/list.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/list.py
@@ -1,7 +1,10 @@
 import json
 import helpers
 
+from wptserve.utils import isomorphic_decode
+
 def main(request, response):
     headers = helpers.setNoCacheAndCORSHeaders(request, response)
     cookies = helpers.readCookies(request)
-    return headers, json.dumps(cookies)
+    decoded_cookies = {isomorphic_decode(key): isomorphic_decode(val) for key, val in cookies.items()}
+    return headers, json.dumps(decoded_cookies)
diff --git a/tests/wpt/web-platform-tests/cookies/resources/postToParent.py b/tests/wpt/web-platform-tests/cookies/resources/postToParent.py
index 3b361601f6f..d1c3ddecaad 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/postToParent.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/postToParent.py
@@ -1,12 +1,14 @@
 import json
 import helpers
 
+from wptserve.utils import isomorphic_decode
+
 def main(request, response):
     headers = helpers.setNoCacheAndCORSHeaders(request, response)
     cookies = helpers.readCookies(request)
-    headers.append(("Content-Type", "text/html; charset=utf-8"))
+    headers.append((b"Content-Type", b"text/html; charset=utf-8"))
 
-    tmpl = """
+    tmpl = u"""
 <!DOCTYPE html>
 <script>
   var data = %s;
@@ -33,4 +35,5 @@ def main(request, response):
   });
 </script>
 """
-    return headers, tmpl % json.dumps(cookies)
+    decoded_cookies = {isomorphic_decode(key): isomorphic_decode(val) for key, val in cookies.items()}
+    return headers, tmpl % json.dumps(decoded_cookies)
diff --git a/tests/wpt/web-platform-tests/cookies/resources/redirectWithCORSHeaders.py b/tests/wpt/web-platform-tests/cookies/resources/redirectWithCORSHeaders.py
index 89ca1af9d80..535cc0ff035 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/redirectWithCORSHeaders.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/redirectWithCORSHeaders.py
@@ -8,15 +8,15 @@ def main(request, response):
     location - The resource to redirect to.
     """
     status = 302
-    if "status" in request.GET:
+    if b"status" in request.GET:
         try:
-            status = int(request.GET.first("status"))
+            status = int(request.GET.first(b"status"))
         except ValueError:
             pass
     headers = setNoCacheAndCORSHeaders(request, response)
 
-    location = request.GET.first("location")
+    location = request.GET.first(b"location")
 
-    headers.append(("Location", location))
+    headers.append((b"Location", location))
 
-    return status, headers, ""
+    return status, headers, b""
diff --git a/tests/wpt/web-platform-tests/cookies/resources/set.py b/tests/wpt/web-platform-tests/cookies/resources/set.py
index 5b6d0b9a2cc..fedf6f3df61 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/set.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/set.py
@@ -1,5 +1,7 @@
 import helpers
-import urllib
+from six.moves.urllib.parse import unquote
+
+from wptserve.utils import isomorphic_encode
 
 def main(request, response):
     """Respond to `/cookie/set?{cookie}` by echoing `{cookie}` as a `Set-Cookie` header."""
@@ -7,7 +9,7 @@ def main(request, response):
 
     # Cookies may require whitespace (e.g. in the `Expires` attribute), so the
     # query string should be decoded.
-    cookie = urllib.unquote(request.url_parts.query)
-    headers.append(("Set-Cookie", cookie))
+    cookie = unquote(request.url_parts.query)
+    headers.append((b"Set-Cookie", isomorphic_encode(cookie)))
 
-    return headers, '{"success": true}'
+    return headers, b'{"success": true}'
diff --git a/tests/wpt/web-platform-tests/cookies/resources/setSameSite.py b/tests/wpt/web-platform-tests/cookies/resources/setSameSite.py
index c2045f7dce1..58572ac5954 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/setSameSite.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/setSameSite.py
@@ -1,5 +1,7 @@
 from helpers import makeCookieHeader, setNoCacheAndCORSHeaders
 
+from wptserve.utils import isomorphic_encode
+
 def main(request, response):
     """Respond to `/cookie/set/samesite?{value}` by setting four cookies:
     1. `samesite_strict={value};SameSite=Strict;path=/`
@@ -8,16 +10,16 @@ def main(request, response):
     4. `samesite_unspecified={value};path=/`
     Then navigate to a page that will post a message back to the opener with the set cookies"""
     headers = setNoCacheAndCORSHeaders(request, response)
-    value = request.url_parts.query
+    value = isomorphic_encode(request.url_parts.query)
 
-    headers.append(("Content-Type", "text/html; charset=utf-8"))
-    headers.append(makeCookieHeader("samesite_strict", value, {"SameSite":"Strict","path":"/"}))
-    headers.append(makeCookieHeader("samesite_lax", value, {"SameSite":"Lax","path":"/"}))
+    headers.append((b"Content-Type", b"text/html; charset=utf-8"))
+    headers.append(makeCookieHeader(b"samesite_strict", value, {b"SameSite":b"Strict", b"path":b"/"}))
+    headers.append(makeCookieHeader(b"samesite_lax", value, {b"SameSite":b"Lax", b"path":b"/"}))
     # SameSite=None cookies must be Secure.
-    headers.append(makeCookieHeader("samesite_none", value, {"SameSite":"None", "path":"/", "Secure": ""}))
-    headers.append(makeCookieHeader("samesite_unspecified", value, {"path":"/"}))
+    headers.append(makeCookieHeader(b"samesite_none", value, {b"SameSite":b"None", b"path":b"/", b"Secure": b""}))
+    headers.append(makeCookieHeader(b"samesite_unspecified", value, {b"path":b"/"}))
 
-    document = """
+    document = b"""
 <!DOCTYPE html>
 <script>
   // A same-site navigation, which should attach all cookies including SameSite ones.
diff --git a/tests/wpt/web-platform-tests/cookies/resources/setSameSiteNone.py b/tests/wpt/web-platform-tests/cookies/resources/setSameSiteNone.py
index e96cbc22e08..574cbb47c19 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/setSameSiteNone.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/setSameSiteNone.py
@@ -1,14 +1,16 @@
 from helpers import makeCookieHeader, setNoCacheAndCORSHeaders
 
+from wptserve.utils import isomorphic_encode
+
 def main(request, response):
     """Respond to `/cookies/resources/setSameSiteNone.py?{value}` by setting two cookies:
     1. `samesite_none_insecure={value};SameSite=None;path=/`
     2. `samesite_none_secure={value};SameSite=None;Secure;path=/`
     """
     headers = setNoCacheAndCORSHeaders(request, response)
-    value = request.url_parts.query
+    value = isomorphic_encode(request.url_parts.query)
 
-    headers.append(makeCookieHeader("samesite_none_insecure", value, {"SameSite":"None", "path":"/"}))
-    headers.append(makeCookieHeader("samesite_none_secure", value, {"SameSite":"None", "Secure":"", "path":"/"}))
+    headers.append(makeCookieHeader(b"samesite_none_insecure", value, {b"SameSite":b"None", b"path":b"/"}))
+    headers.append(makeCookieHeader(b"samesite_none_secure", value, {b"SameSite":b"None", b"Secure":b"", b"path":b"/"}))
 
-    return headers, '{"success": true}'
+    return headers, b'{"success": true}'
diff --git a/tests/wpt/web-platform-tests/cookies/resources/setSecure.py b/tests/wpt/web-platform-tests/cookies/resources/setSecure.py
index c8ec017627a..633e21aac8e 100644
--- a/tests/wpt/web-platform-tests/cookies/resources/setSecure.py
+++ b/tests/wpt/web-platform-tests/cookies/resources/setSecure.py
@@ -1,12 +1,14 @@
 from helpers import makeCookieHeader, readParameter, setNoCacheAndCORSHeaders
 
+from wptserve.utils import isomorphic_encode
+
 def main(request, response):
     """Respond to `/cookie/set/secure?{value}` by setting two cookies:
     alone_secure={value};secure;path=/`
     alone_insecure={value};path=/"""
     headers = setNoCacheAndCORSHeaders(request, response)
-    value = request.url_parts.query
+    value = isomorphic_encode(request.url_parts.query)
 
-    headers.append(makeCookieHeader("alone_secure", value, {"secure": "","path": "/"}))
-    headers.append(makeCookieHeader("alone_insecure", value, {"path": "/"}))
-    return headers, '{"success": true}'
+    headers.append(makeCookieHeader(b"alone_secure", value, {b"secure": b"", b"path": b"/"}))
+    headers.append(makeCookieHeader(b"alone_insecure", value, {b"path": b"/"}))
+    return headers, b'{"success": true}'
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/border-image-image-type-003.htm b/tests/wpt/web-platform-tests/css/css-backgrounds/border-image-image-type-003.htm
index b2710c15e8c..e59785df929 100644
Binary files a/tests/wpt/web-platform-tests/css/css-backgrounds/border-image-image-type-003.htm and b/tests/wpt/web-platform-tests/css/css-backgrounds/border-image-image-type-003.htm differ
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/reference/border-image-image-type-003-ref.html b/tests/wpt/web-platform-tests/css/css-backgrounds/reference/border-image-image-type-003-ref.html
new file mode 100644
index 00000000000..690f9ad11ad
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/reference/border-image-image-type-003-ref.html
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+
+  <meta charset="UTF-8">
+
+  <title>CSS Reference Test</title>
+
+  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
+
+  <style>
+  div#outer
+    {
+      background-image: linear-gradient(to top, blue, orange);
+      height: 140px;
+      margin: 10px;
+      width: 140px;
+    }
+
+  div#inner
+    {
+      background-color: white;
+      height: 80px;
+      left: 30px;
+      position: relative;
+      top: 30px;
+      width: 80px;
+    }
+  </style>
+
+  <p>Test passes if there is no red visible on the page.
+
+  <div id="outer"><div id="inner"></div></div>
diff --git a/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-000.html b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-000.html
new file mode 100644
index 00000000000..4836f399de4
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-000.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#possible-breaks">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<meta name="assert" content="We should break between the two lines (class B breakpoint), rather than between the last line and the container padding">
+<style>
+  .child { display:inline-block; vertical-align:top; width:100%; height:50px; line-height:50px; }
+</style>
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:2; column-fill:auto; column-gap:0; width:100px; height:100px; orphans:1; widows:1; background:red;">
+  <div style="padding-bottom:50px; background:green;">
+    <div class="child"></div>
+    <div class="child"></div>
+  </div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-001.html b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-001.html
new file mode 100644
index 00000000000..d6d3374bc77
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-001.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#possible-breaks">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<meta name="assert" content="We should break between the last two lines (class B breakpoint), rather than inside the container padding">
+<style>
+  .child { display:inline-block; vertical-align:top; width:100%; height:30px; line-height:30px; }
+</style>
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:2; column-fill:auto; column-gap:0; width:100px; height:100px; orphans:1; widows:1; background:red;">
+  <div style="padding-bottom:70px; background:green;">
+    <div class="child"></div>
+    <div class="child"></div>
+    <div class="child"></div>
+  </div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-002.html b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-002.html
new file mode 100644
index 00000000000..0002a558a1e
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-002.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#possible-breaks">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<meta name="assert" content="We should break between the first two lines (class B breakpoint, also honoring widows), rather than inside the container padding">
+<style>
+  .child { display:inline-block; vertical-align:top; width:100%; height:30px; line-height:30px; }
+</style>
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:2; column-fill:auto; column-gap:0; width:100px; height:100px; orphans:1; widows:2; background:red;">
+  <div style="padding-bottom:40px; background:green;">
+    <div class="child"></div>
+    <div class="child"></div>
+    <div class="child"></div>
+  </div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-003.html b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-003.html
new file mode 100644
index 00000000000..aafe3975ee0
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-003.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#possible-breaks">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<meta name="assert" content="The block with padding should be pushed to the second column, so that we won't have to break between the line and the padding edge">
+<style>
+  .child { display:inline-block; vertical-align:top; width:100%; height:90px; line-height:90px; }
+</style>
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:2; column-fill:auto; column-gap:0; width:100px; height:100px; orphans:1; widows:1; background:red;">
+  <div style="float:left; width:100%; height:100px; background:green;"></div>
+  <div style="height:10px;"></div>
+  <div style="padding-bottom:10px; background:green;">
+    <div class="child"></div>
+  </div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-004.html b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-004.html
new file mode 100644
index 00000000000..c9d8b8fad5b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-break/break-at-end-container-edge-004.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#possible-breaks">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<meta name="assert" content="The last line could fit in the third column, but will be pushed to the fourth, so that we won't have to break between the last line and the container padding">
+<style>
+  .child { display:inline-block; vertical-align:top; width:100%; height:40px; line-height:40px; }
+</style>
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:4; column-fill:auto; column-gap:0; width:100px; height:100px; orphans:1; widows:1; background:red;">
+  <div style="height:40px; background:green;"></div>
+  <div style="padding-bottom:60px; background:green;">
+    <div class="child"></div>
+    <div class="child"></div>
+    <div class="child"></div>
+    <div class="child"></div>
+    <div class="child"></div>
+  </div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-break/tall-line-in-short-fragmentainer-000.html b/tests/wpt/web-platform-tests/css/css-break/tall-line-in-short-fragmentainer-000.html
new file mode 100644
index 00000000000..8e9515c4b6c
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-break/tall-line-in-short-fragmentainer-000.html
@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#unforced-breaks">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:3; column-fill:auto; column-gap:0; width:300px; height:50px;">
+  <div style="width:200px; height:0;">
+    <div style="height:20px; background:red;"></div>
+  </div>
+  <!-- No valid breakpoint here, since the preceding sibling takes up no space
+       (and its overflowing child ends up in a parallel flow). -->
+  <div style="height:120px;">
+    <!-- Can't break inside lines. Let it overflow the (shorter) fragmentainer,
+         but not its container. Consume 100px from it. -->
+    <div style="display:inline-block; vertical-align:top; width:100px; height:100px; background:green;"></div>
+  </div>
+  <div style="margin-top:-20px; height:20px; background:white;"></div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-break/tall-line-in-short-fragmentainer-001.html b/tests/wpt/web-platform-tests/css/css-break/tall-line-in-short-fragmentainer-001.html
new file mode 100644
index 00000000000..8f74878187a
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-break/tall-line-in-short-fragmentainer-001.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#unforced-breaks">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:2; column-fill:auto; column-gap:0; width:100px; height:50px; background:red;">
+  <div>
+    <div style="display:inline-block; vertical-align:top; width:50px; height:100px; background:green;"></div>
+  </div>
+  <!-- We're at the very beginning of the second column here, so inserting a
+       forced break will have no effect. -->
+  <div style="break-before:column;">
+    <div style="display:inline-block; vertical-align:top; width:50px; height:100px; background:green;"></div>
+  </div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-break/tall-line-in-short-fragmentainer-002.html b/tests/wpt/web-platform-tests/css/css-break/tall-line-in-short-fragmentainer-002.html
new file mode 100644
index 00000000000..ee277549633
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-break/tall-line-in-short-fragmentainer-002.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#unforced-breaks">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:2; column-fill:auto; column-gap:0; width:100px; height:50px; background:red;">
+  <div style="width:50px; height:100px; line-height:200px; background:green;">
+    <br>
+  </div>
+  <div style="break-before:column; width:50px; line-height:100px; background:green;">
+    <br>
+  </div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-multicol/column-balancing-paged-001-print-ref.html b/tests/wpt/web-platform-tests/css/css-multicol/column-balancing-paged-001-print-ref.html
new file mode 100644
index 00000000000..af1a86b1e73
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-multicol/column-balancing-paged-001-print-ref.html
@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<html>
+  <meta charset="utf-8">
+  <title>CSS Multi-column Layout Test Reference: Test fragmentation for a nested multi-column container with column-span in paginated context</title>
+  <link rel="author" title="Ting-Yu Lin" href="tlin@mozilla.com">
+  <link rel="author" title="Mozilla" href="https://www.mozilla.org/">
+
+  <style>
+  .inner {
+    column-count: 2;
+    column-rule: 3px solid green;
+    background-color: lightgreen;
+  }
+  .block1 {
+    background-color: yellow;
+    height: 3in;
+  }
+  .spanner {
+    height: 2in;
+    background-color: lightblue;
+  }
+  .block2 {
+    background-color: pink;
+    height: 3in;
+  }
+  </style>
+
+  <article class="inner">
+    <div class="block1">block1</div>
+  </article>
+  <div class="spanner">spanner</div>
+  <article class="inner">
+    <div class="block2">block2</div>
+  </article>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-multicol/column-balancing-paged-001-print.html b/tests/wpt/web-platform-tests/css/css-multicol/column-balancing-paged-001-print.html
new file mode 100644
index 00000000000..cf8e343d0ff
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-multicol/column-balancing-paged-001-print.html
@@ -0,0 +1,43 @@
+<!DOCTYPE html>
+<html>
+  <meta charset="utf-8">
+  <title>CSS Multi-column Layout Test: Test fragmentation for a nested multi-column container with column-span in paginated context</title>
+  <link rel="match" href="column-balancing-paged-001-print-ref.html">
+  <link rel="author" title="Ting-Yu Lin" href="tlin@mozilla.com">
+  <link rel="author" title="Mozilla" href="http://www.mozilla.org/">
+  <link rel="help" href="https://drafts.csswg.org/css-multicol-1/#column-span">
+  <link rel="help" href="https://drafts.csswg.org/css-break/#breaking-rules">
+
+  <style>
+  .outer {
+    column-count: 1;
+    column-rule: 6px solid black;
+  }
+  .inner {
+    column-count: 2;
+    column-rule: 3px solid green;
+    background-color: lightgreen;
+  }
+  .block1 {
+    background-color: yellow;
+    height: 3in;
+  }
+  .spanner {
+    column-span: all;
+    height: 2in;
+    background-color: lightblue;
+  }
+  .block2 {
+    background-color: pink;
+    height: 3in
+  }
+  </style>
+
+  <article class="outer">
+    <article class="inner">
+      <div class="block1">block1</div>
+      <div class="spanner">spanner</div>
+      <div class="block2">block2</div>
+    </article>
+  </article>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-position/nested-positions-crash.html b/tests/wpt/web-platform-tests/css/css-position/nested-positions-crash.html
new file mode 100644
index 00000000000..dbc272fa093
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-position/nested-positions-crash.html
@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<link rel="help" href="https://crbug.com/1098840">
+<title>Verifies changing 'display' nested positions is not problematic</title>
+<div style="position:absolute; display:table;">
+  <div style="position:fixed;"></div>
+</div>
+<span></span>
+<div id="boom" style="display:none;"></div>
+<script>
+  document.body.offsetTop;
+  boom.style.display = "block";
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-pseudo/marker-text-combine-upright-ref.html b/tests/wpt/web-platform-tests/css/css-pseudo/marker-text-combine-upright-ref.html
new file mode 100644
index 00000000000..2ad96e37bb1
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-pseudo/marker-text-combine-upright-ref.html
@@ -0,0 +1,36 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Reference: ::marker supports 'text-combine-upright'</title>
+<style>
+body {
+  writing-mode: vertical-lr;
+}
+ol, ul {
+  display: flow-root;
+  list-style-type: none;
+}
+.symbol {
+  list-style-type: disc;
+}
+ul {
+  list-style-position: inside;
+}
+ol span {
+  display: inline-block;
+  margin-top: -50px;
+  height: 50px;
+  text-align: end;
+}
+span {
+  text-combine-upright: all;
+}
+</style>
+<ol><li><span>1. </span>outside decimal</li></ol>
+<ol><li><span>2. </span>outside string</li></ol>
+<ol><li><span>3. </span>outside content</li></ol>
+<ol class="symbol"><li>outside symbol</li></ol>
+
+<ul><li><span>1. </span>inside decimal</li></ul>
+<ul><li><span>2. </span>inside string</li></ul>
+<ul><li><span>3. </span>inside content</li></ul>
+<ul class="symbol"><li>inside symbol</li></ul>
diff --git a/tests/wpt/web-platform-tests/css/css-pseudo/marker-text-combine-upright.html b/tests/wpt/web-platform-tests/css/css-pseudo/marker-text-combine-upright.html
new file mode 100644
index 00000000000..64b37a0c7d4
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-pseudo/marker-text-combine-upright.html
@@ -0,0 +1,43 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Test: ::marker supports 'text-combine-upright'</title>
+<link rel="author" title="Oriol Brufau" href="mailto:obrufau@igalia.com">
+<link rel="match" href="marker-text-combine-upright-ref.html">
+<link rel="help" href="https://drafts.csswg.org/css-pseudo-4/#marker-pseudo">
+<link rel="help" href="https://drafts.csswg.org/css-writing-modes-4/#propdef-text-combine-upright">
+<meta name="assert" content="Checks that 'text-combine-upright' works well in ::marker, and doesn't crash.">
+<style>
+body {
+  writing-mode: vertical-lr;
+}
+ol, ul {
+  display: flow-root;
+}
+ul {
+  list-style-position: inside;
+}
+.decimal {
+  list-style-type: decimal;
+}
+.string {
+  list-style-type: "2. ";
+}
+.content ::marker {
+  content: "3. ";
+}
+.symbol {
+  list-style-type: disc;
+}
+::marker {
+  text-combine-upright: all;
+}
+</style>
+<ol class="decimal"><li>outside decimal</li></ol>
+<ol class="string"><li>outside string</li></ol>
+<ol class="content"><li>outside content</li></ol>
+<ol class="symbol"><li>outside symbol</li></ol>
+
+<ul class="decimal"><li>inside decimal</li></ul>
+<ul class="string"><li>inside string</li></ul>
+<ul class="content"><li>inside content</li></ul>
+<ul class="symbol"><li>inside symbol</li></ul>
diff --git a/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-auto-010.html b/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-auto-010.html
index 60ad082b8b4..01acaf0c9ba 100644
--- a/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-auto-010.html
+++ b/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-auto-010.html
@@ -6,7 +6,18 @@
 
   <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
   <link rel="help" href="https://www.w3.org/TR/css-text-3/#hyphenation">
-  <link rel="match" href="reference/hyphens-auto-010-ref.html">
+  <link rel="match" href="reference/hyphens-auto-010M-ref.html">
+  <link rel="match" href="reference/hyphens-auto-010H-ref.html">
+
+  <!--
+  User agents may use U+2010 HYPHEN <https://codepoints.net/U+2010>
+  when the font has the glyph, or
+  may use U+002D HYPHEN-MINUS <https://codepoints.net/U+002d>
+  otherwise. Some fonts will display slightly different glyphs for
+  these code points. Therefore these 2 reference files.
+  The M-ref.html reference file means the hyphen-Minus character U+002D.
+  The H-ref.html reference file means the Hyphen character U+2010.
+  -->
 
   <meta content="" name="flags">
   <meta content="When 'hyphens' is set to 'auto' and when 'lang' attribute is also set to a valid value, then words may be broken at hyphenation opportunities determined automatically by an hyphenation resource appropriate to the language of the text involved.">
@@ -17,25 +28,11 @@
       border: black solid 2px;
       font-family: monospace;
       font-size: 32px;
-      margin-bottom: 0.25em;
-      width: 6ch;
-    }
-
-  div#test
-    {
       hyphens: auto;
-    }
-
-  div#reference
-    {
-      hyphens: none;
+      width: 6ch;
     }
   </style>
 
  <body lang="en">
 
-  <p>Test passes if each black-bordered rectangles have identical inside content.
-
-  <div id="test">regulation implementation</div>
-
-  <div id="reference">regu-lation imple-menta-tion</div>
+  <div>regulation implementation</div>
diff --git a/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-none-012.html b/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-none-012.html
index 9c5c5d693c0..5b70c95e4e1 100644
--- a/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-none-012.html
+++ b/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-none-012.html
@@ -6,7 +6,7 @@
 
   <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
   <link rel="help" href="https://www.w3.org/TR/css-text-3/#hyphenation">
-  <link rel="match" href="reference/hyphens-auto-010-ref.html">
+  <link rel="match" href="reference/hyphens-auto-010M-ref.html">
 
   <meta content="" name="flags">
   <meta content="This test checks that 'hyphens: none' does not suppress line wrapping after encountering an actual hyphen-minus character (U+002D).">
@@ -17,28 +17,18 @@
       border: black solid 2px;
       font-family: monospace;
       font-size: 32px;
-      margin-bottom: 0.25em;
-      width: 6ch;
-    }
-
-  div#test
-    {
       hyphens: none;
+      width: 6ch;
     }
   </style>
 
- <body>
+  <div>regu&#x002D;lation imple&#x002D;menta&#x002D;tion</div>
 
-  <p>Test passes if each black-bordered rectangles have identical inside content.
-
-  <div id="test">regu-lation imple-menta-tion</div>
-
-  <div id="reference">regu&#x002D;<br>lation<br>imple&#x002D;<br>menta&#x002D;<br>tion</div>
-
-<!--
-
-  Hyphen-minus == &#x002D; == &#0045;
-
-  Hyphen == &#x2010; == &#8208;
-
--->
+  <!--
+        Expected result:
+        regu-
+        lation
+        imple-
+        menta-
+        tion
+  -->
diff --git a/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-none-013.html b/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-none-013.html
index ba3286f085a..d234cc0d095 100644
--- a/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-none-013.html
+++ b/tests/wpt/web-platform-tests/css/css-text/hyphens/hyphens-none-013.html
@@ -6,7 +6,7 @@
 
   <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
   <link rel="help" href="https://www.w3.org/TR/css-text-3/#hyphenation">
-  <link rel="match" href="reference/hyphens-auto-010-ref.html">
+  <link rel="match" href="reference/hyphens-auto-010H-ref.html">
 
   <meta content="" name="flags">
   <meta content="This test checks that 'hyphens: none' does not suppress line wrapping after encountering an actual hyphen character (U+2010).">
@@ -17,28 +17,18 @@
       border: black solid 2px;
       font-family: monospace;
       font-size: 32px;
-      margin-bottom: 0.25em;
-      width: 6ch;
-    }
-
-  div#test
-    {
       hyphens: none;
+      width: 6ch;
     }
   </style>
 
- <body>
+  <div>regu&#x2010;lation imple&#x2010;menta&#x2010;tion</div>
 
-  <p>Test passes if each black-bordered rectangles have identical inside content.
-
-  <div id="test">regu-lation imple-menta-tion</div>
-
-  <div id="reference">regu&#x2010;<br>lation<br>imple&#x2010;<br>menta&#x2010;<br>tion</div>
-
-<!--
-
-  Hyphen-minus == &#x002D; == &#0045;
-
-  Hyphen == &#x2010; == &#8208;
-
--->
+  <!--
+        Expected result:
+        regu-
+        lation
+        imple-
+        menta-
+        tion
+  -->
diff --git a/tests/wpt/web-platform-tests/css/css-text/hyphens/reference/hyphens-auto-010-ref.html b/tests/wpt/web-platform-tests/css/css-text/hyphens/reference/hyphens-auto-010H-ref.html
similarity index 62%
rename from tests/wpt/web-platform-tests/css/css-text/hyphens/reference/hyphens-auto-010-ref.html
rename to tests/wpt/web-platform-tests/css/css-text/hyphens/reference/hyphens-auto-010H-ref.html
index 13841121c64..861f0ed9d07 100644
--- a/tests/wpt/web-platform-tests/css/css-text/hyphens/reference/hyphens-auto-010-ref.html
+++ b/tests/wpt/web-platform-tests/css/css-text/hyphens/reference/hyphens-auto-010H-ref.html
@@ -12,16 +12,18 @@
       border: black solid 2px;
       font-family: monospace;
       font-size: 32px;
-      hyphens: none;
-      margin-bottom: 0.25em;
       width: 6ch;
     }
   </style>
 
  <body lang="en">
 
-  <p>Test passes if each black-bordered rectangles have identical inside content.
+  <div>regu&#x2010;<br>lation<br>imple&#x2010;<br>menta&#x2010;<br>tion</div>
 
-  <div>regu-lation imple-menta-tion</div>
+<!--
 
-  <div>regu-lation imple-menta-tion</div>
+  Hyphen-minus == &#x002D; == &#0045;
+
+  Hyphen == &#x2010; == &#8208;
+
+-->
diff --git a/tests/wpt/web-platform-tests/css/css-text/hyphens/reference/hyphens-auto-010M-ref.html b/tests/wpt/web-platform-tests/css/css-text/hyphens/reference/hyphens-auto-010M-ref.html
new file mode 100644
index 00000000000..d6c0065eb88
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-text/hyphens/reference/hyphens-auto-010M-ref.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+
+  <meta charset="UTF-8">
+
+  <title>CSS Reference Test</title>
+
+  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
+
+  <style>
+  div
+    {
+      border: black solid 2px;
+      font-family: monospace;
+      font-size: 32px;
+      width: 6ch;
+    }
+  </style>
+
+ <body lang="en">
+
+  <div>regu&#x002D;<br>lation<br>imple&#x002D;<br>menta&#x002D;<br>tion</div>
+
+<!--
+
+  Hyphen-minus == &#x002D; == &#0045;
+
+  Hyphen == &#x2010; == &#8208;
+
+-->
diff --git a/tests/wpt/web-platform-tests/event-timing/resources/slow-image.py b/tests/wpt/web-platform-tests/event-timing/resources/slow-image.py
index 5c2d1b1fc5d..c2f91655cf3 100644
--- a/tests/wpt/web-platform-tests/event-timing/resources/slow-image.py
+++ b/tests/wpt/web-platform-tests/event-timing/resources/slow-image.py
@@ -3,5 +3,5 @@ import time
 def main(request, response):
     # Sleep for 500ms to delay onload.
     time.sleep(0.5)
-    response.headers.set("Cache-Control", "no-cache, must-revalidate");
-    response.headers.set("Location", "data:image/gif;base64,R0lGODlhAQABAJAAAMjIyAAAACwAAAAAAQABAAACAgQBADs%3D");
+    response.headers.set(b"Cache-Control", b"no-cache, must-revalidate");
+    response.headers.set(b"Location", b"data:image/gif;base64,R0lGODlhAQABAJAAAMjIyAAAACwAAAAAAQABAAACAgQBADs%3D");
diff --git a/tests/wpt/web-platform-tests/fetch/api/resources/redirect.py b/tests/wpt/web-platform-tests/fetch/api/resources/redirect.py
index 05129c515ad..c8d481ebd33 100644
--- a/tests/wpt/web-platform-tests/fetch/api/resources/redirect.py
+++ b/tests/wpt/web-platform-tests/fetch/api/resources/redirect.py
@@ -2,68 +2,70 @@ import time
 
 from six.moves.urllib.parse import urlencode, urlparse
 
+from wptserve.utils import isomorphic_decode, isomorphic_encode
+
 def main(request, response):
-    stashed_data = {'count': 0, 'preflight': "0"}
+    stashed_data = {b'count': 0, b'preflight': b"0"}
     status = 302
-    headers = [("Content-Type", "text/plain"),
-               ("Cache-Control", "no-cache"),
-               ("Pragma", "no-cache")]
-    if "Origin" in request.headers:
-        headers.append(("Access-Control-Allow-Origin", request.headers.get("Origin", "")))
-        headers.append(("Access-Control-Allow-Credentials", "true"))
+    headers = [(b"Content-Type", b"text/plain"),
+               (b"Cache-Control", b"no-cache"),
+               (b"Pragma", b"no-cache")]
+    if b"Origin" in request.headers:
+        headers.append((b"Access-Control-Allow-Origin", request.headers.get(b"Origin", b"")))
+        headers.append((b"Access-Control-Allow-Credentials", b"true"))
     else:
-        headers.append(("Access-Control-Allow-Origin", "*"))
+        headers.append((b"Access-Control-Allow-Origin", b"*"))
 
     token = None
-    if "token" in request.GET:
-        token = request.GET.first("token")
+    if b"token" in request.GET:
+        token = request.GET.first(b"token")
         data = request.server.stash.take(token)
         if data:
             stashed_data = data
 
-    if request.method == "OPTIONS":
-        if "allow_headers" in request.GET:
-            headers.append(("Access-Control-Allow-Headers", request.GET['allow_headers']))
-        stashed_data['preflight'] = "1"
+    if request.method == u"OPTIONS":
+        if b"allow_headers" in request.GET:
+            headers.append((b"Access-Control-Allow-Headers", request.GET[b'allow_headers']))
+        stashed_data[b'preflight'] = b"1"
         #Preflight is not redirected: return 200
-        if not "redirect_preflight" in request.GET:
+        if not b"redirect_preflight" in request.GET:
             if token:
-                request.server.stash.put(request.GET.first("token"), stashed_data)
-            return 200, headers, ""
+                request.server.stash.put(request.GET.first(b"token"), stashed_data)
+            return 200, headers, u""
 
-    if "redirect_status" in request.GET:
-        status = int(request.GET['redirect_status'])
+    if b"redirect_status" in request.GET:
+        status = int(request.GET[b'redirect_status'])
 
-    stashed_data['count'] += 1
+    stashed_data[b'count'] += 1
 
-    if "location" in request.GET:
-        url = request.GET['location']
-        if "simple" not in request.GET:
+    if b"location" in request.GET:
+        url = isomorphic_decode(request.GET[b'location'])
+        if b"simple" not in request.GET:
             scheme = urlparse(url).scheme
-            if scheme == "" or scheme == "http" or scheme == "https":
-                url += "&" if '?' in url else "?"
+            if scheme == u"" or scheme == u"http" or scheme == u"https":
+                url += u"&" if u'?' in url else u"?"
                 #keep url parameters in location
                 url_parameters = {}
                 for item in request.GET.items():
-                    url_parameters[item[0]] = item[1][0]
+                    url_parameters[isomorphic_decode(item[0])] = isomorphic_decode(item[1][0])
                 url += urlencode(url_parameters)
                 #make sure location changes during redirection loop
-                url += "&count=" + str(stashed_data['count'])
-        headers.append(("Location", url))
+                url += u"&count=" + str(stashed_data[b'count'])
+        headers.append((b"Location", isomorphic_encode(url)))
 
-    if "redirect_referrerpolicy" in request.GET:
-        headers.append(("Referrer-Policy", request.GET['redirect_referrerpolicy']))
+    if b"redirect_referrerpolicy" in request.GET:
+        headers.append((b"Referrer-Policy", request.GET[b'redirect_referrerpolicy']))
 
-    if "delay" in request.GET:
-        time.sleep(float(request.GET.first("delay", 0)) / 1E3)
+    if b"delay" in request.GET:
+        time.sleep(float(request.GET.first(b"delay", 0)) / 1E3)
 
     if token:
-        request.server.stash.put(request.GET.first("token"), stashed_data)
-        if "max_count" in request.GET:
-            max_count = int(request.GET['max_count'])
+        request.server.stash.put(request.GET.first(b"token"), stashed_data)
+        if b"max_count" in request.GET:
+            max_count = int(request.GET[b'max_count'])
             #stop redirecting and return count
-            if stashed_data['count'] > max_count:
+            if stashed_data[b'count'] > max_count:
                 # -1 because the last is not a redirection
-                return str(stashed_data['count'] - 1)
+                return str(stashed_data[b'count'] - 1)
 
-    return status, headers, ""
+    return status, headers, u""
diff --git a/tests/wpt/web-platform-tests/fullscreen/api/element-request-fullscreen-options.tentative.html b/tests/wpt/web-platform-tests/fullscreen/api/element-request-fullscreen-options.tentative.html
new file mode 100644
index 00000000000..3646a6f0e9f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/fullscreen/api/element-request-fullscreen-options.tentative.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<title>Element#requestFullscreen({ screen }) tentative support</title>
+<!-- TODO: update link to W3C whenever specifications are ready -->
+<link rel="help" href="https://github.com/webscreens/window-placement"/>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+promise_test(async t => {
+  // Grant window-placement permissions for testdriver.
+  await test_driver.set_permission({name: "window-placement"}, "granted");
+
+  let invoked = false;
+  let options = { get screen() { invoked = true; return undefined; } };
+  return document.body.requestFullscreen(options).then(
+    () => { assert_unreached("promise unexpectedly fulfilled"); },
+    () => { assert_true(invoked, "screen getter not invoked"); });
+}, "fullscreenOptions.screen getter is invoked on requestFullscreen");
+</script>
diff --git a/tests/wpt/web-platform-tests/html/cross-origin-embedder-policy/reporting-navigation.https.html b/tests/wpt/web-platform-tests/html/cross-origin-embedder-policy/reporting-navigation.https.html
index 2baf1755f0c..7087985990e 100644
--- a/tests/wpt/web-platform-tests/html/cross-origin-embedder-policy/reporting-navigation.https.html
+++ b/tests/wpt/web-platform-tests/html/cross-origin-embedder-policy/reporting-navigation.https.html
@@ -69,8 +69,8 @@ async function observeReports(global) {
   });
   observer.observe();
 
-  // Wait 3000ms for reports to settle.
-  await new Promise(r => step_timeout(r, 3000));
+  // Wait 5000ms for reports to settle.
+  await new Promise(r => step_timeout(r, 5000));
   return reports;
 }
 
diff --git a/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-after-1-print.html b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-after-1-print.html
new file mode 100644
index 00000000000..cb7fc466d09
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-after-1-print.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+
+<html>
+  <link rel="match" href="details-two-pages-print-ref.html">
+  <link rel="help" href="https://html.spec.whatwg.org/multipage/rendering.html#the-details-and-summary-elements">
+  <style>
+  summary {
+    /* Hide the triangle for comparing with div in reftest. */
+    list-style-type: none;
+  }
+  </style>
+  <body>
+    <details open>
+      <summary style="page-break-after: always;">Summary</summary>
+      <p>This is the details.</p>
+    </details>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-after-2-print.html b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-after-2-print.html
new file mode 100644
index 00000000000..2f3d12bbe3b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-after-2-print.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+
+<html>
+  <link rel="match" href="details-two-pages-print-ref.html">
+  <link rel="help" href="https://html.spec.whatwg.org/multipage/rendering.html#the-details-and-summary-elements">
+  <style>
+  summary {
+    /* Hide the triangle for comparing with div in reftest. */
+    list-style-type: none;
+  }
+  </style>
+  <body>
+    <details open>
+      <summary>Summary<div style="page-break-before: always;"></div></summary>
+      <p>This is the details.</p>
+    </details>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-before-1-print.html b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-before-1-print.html
new file mode 100644
index 00000000000..5abf4c39ae0
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-before-1-print.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+
+<html>
+  <link rel="match" href="details-two-pages-print-ref.html">
+  <link rel="help" href="https://html.spec.whatwg.org/multipage/rendering.html#the-details-and-summary-elements">
+  <style>
+  summary {
+    /* Hide the triangle for comparing with div in reftest. */
+    list-style-type: none;
+  }
+  </style>
+  <body>
+    <details open>
+      <summary>Summary</summary>
+      <p style="page-break-before: always;">This is the details.</p>
+    </details>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-before-2-print.html b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-before-2-print.html
new file mode 100644
index 00000000000..2f3d12bbe3b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-page-break-before-2-print.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+
+<html>
+  <link rel="match" href="details-two-pages-print-ref.html">
+  <link rel="help" href="https://html.spec.whatwg.org/multipage/rendering.html#the-details-and-summary-elements">
+  <style>
+  summary {
+    /* Hide the triangle for comparing with div in reftest. */
+    list-style-type: none;
+  }
+  </style>
+  <body>
+    <details open>
+      <summary>Summary<div style="page-break-before: always;"></div></summary>
+      <p>This is the details.</p>
+    </details>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-two-pages-print-ref.html b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-two-pages-print-ref.html
new file mode 100644
index 00000000000..309a138696e
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/rendering/the-details-element/details-two-pages-print-ref.html
@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+
+<html>
+  <body>
+    <div>
+      <div style="page-break-after: always;">Summary</div>
+      <p>This is the details.</p>
+    </div>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/list-of-available-images-matching.https.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/list-of-available-images-matching.https.html
new file mode 100644
index 00000000000..4843d219156
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/list-of-available-images-matching.https.html
@@ -0,0 +1,68 @@
+<!doctype html>
+<html>
+<title>List of available images tuple-matching logic</title>
+<link rel="author" title="Dom Farolino" href="mailto:dom@chromium.org">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#the-list-of-available-images">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/service-workers/service-worker/resources/test-helpers.sub.js"></script>
+<script src="/common/get-host-info.sub.js"></script>
+
+<script>
+const path = location.origin + '/html/semantics/embedded-content/the-img-element/';
+const image_url = path + 'image-1.jpg';
+
+function syncWait(ms) {
+  const start = Date.now();
+  while (Date.now() - start < ms);
+}
+
+let sawNoCorsRequest = false;
+
+navigator.serviceWorker.onmessage = ({data}) => {
+  if (data.url === image_url && data.mode === 'no-cors') {
+    sawNoCorsRequest = true;
+  }
+};
+
+promise_test(t => {
+  return service_worker_unregister_and_register(t, 'resources/sw.js', path)
+    .then(r => {
+      return wait_for_state(t, r.installing, 'activated');
+    });
+}, 'registering service worker');
+
+promise_test(async t => {
+  const img = new Image();
+
+  function load_img_promise() {
+    return new Promise((resolve, reject) => {
+      img.onload = resolve;
+      img.onerror = e => { reject("The img should not fail to load") };
+
+      img.src = image_url;
+      // If there is not a matching image in the list of available images, the
+      // actual fetch operation is queued as a microtask, so we will see a
+      // request with mode 'cors' due to setting the crossorigin attribute
+      // below.
+      syncWait(500);
+      img.crossOrigin = 'anonymous';
+    });
+  };
+
+  await load_img_promise();
+  assert_false(sawNoCorsRequest, "The image is not fetched with mode: no-cors");
+  await new Promise(resolve => {
+    img.onload = img.onerror = resolve;
+    img.src = '';
+    img.crossOrigin = null;
+  });
+  await load_img_promise();
+  assert_false(sawNoCorsRequest, "The image is not fetched with mode: no-cors");
+
+}, 'list of available images tuple-matching logic');
+
+promise_test(t => {
+  return service_worker_unregister(t, path);
+}, 'unregistering service worker');
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/resources/sw.js b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/resources/sw.js
new file mode 100644
index 00000000000..8bd079f7906
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/resources/sw.js
@@ -0,0 +1,20 @@
+addEventListener('install', (event) => {
+  skipWaiting();
+});
+
+addEventListener('activate', (event) => {
+  event.waitUntil(clients.claim());
+});
+
+async function broadcast(msg) {
+  const allClients = await clients.matchAll();
+  for (const client of allClients) {
+    client.postMessage(msg);
+  }
+}
+
+addEventListener('fetch', (event) => {
+  event.waitUntil(
+    broadcast({ url: event.request.url, mode: event.request.mode })
+  )
+});
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/resources/sw.js.headers b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/resources/sw.js.headers
new file mode 100644
index 00000000000..3c534471c8d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/resources/sw.js.headers
@@ -0,0 +1 @@
+Service-Worker-Allowed: /html/semantics/embedded-content/the-img-element/
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/cacheable-script-throw.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/cacheable-script-throw.py
index 5df883c07be..b315afed563 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/cacheable-script-throw.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/cacheable-script-throw.py
@@ -1,4 +1,4 @@
 def main(request, response):
-    headers = [("Content-Type", "text/javascript"), ("Cache-control", "public, max-age=100")]
-    body = "throw('fox');"
+    headers = [(b"Content-Type", b"text/javascript"), (b"Cache-control", b"public, max-age=100")]
+    body = u"throw('fox');"
     return 200, headers, body
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/log.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/log.py
index 6803bb3e405..2a6cc330296 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/log.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/log.py
@@ -1,13 +1,13 @@
 import time
 
 def main(request, response):
-    response.headers.append("Content-Type", "text/javascript")
+    response.headers.append(b"Content-Type", b"text/javascript")
     try:
-        script_id = int(request.GET.first("id"))
-        delay = int(request.GET.first("sec"))
+        script_id = int(request.GET.first(b"id"))
+        delay = int(request.GET.first(b"sec"))
     except:
-        response.set_error(400, "Invalid parameter")
+        response.set_error(400, u"Invalid parameter")
 
     time.sleep(int(delay))
 
-    return "log('%s')" % script_id
+    return u"log('%s')" % script_id
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/module/resources/delayed-modulescript.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/module/resources/delayed-modulescript.py
index 6ed16212d71..52dbfba445e 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/module/resources/delayed-modulescript.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/module/resources/delayed-modulescript.py
@@ -1,7 +1,7 @@
 import time
 
 def main(request, response):
-    delay = float(request.GET.first("ms", 500))
-    time.sleep(delay / 1E3);
+    delay = float(request.GET.first(b"ms", 500))
+    time.sleep(delay / 1E3)
 
-    return [("Content-type", "text/javascript")], "export let delayedLoaded = true;"
+    return [(b"Content-type", b"text/javascript")], u"export let delayedLoaded = true;"
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/moving-between-documents/resources/moving-between-documents-iframe.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/moving-between-documents/resources/moving-between-documents-iframe.py
index e54c3b94528..b7b6dac1937 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/moving-between-documents/resources/moving-between-documents-iframe.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/moving-between-documents/resources/moving-between-documents-iframe.py
@@ -1,22 +1,25 @@
 import random
 import time
 
+from wptserve.utils import isomorphic_decode
+
+
 """
 This script serves
 """
 
 def main(request, response):
-  inlineOrExternal = request.GET.first("inlineOrExternal", "null")
-  hasBlockingStylesheet = request.GET.first("hasBlockingStylesheet", "true") == "true"
-  result = request.GET.first("result", "success")
-  type = "text/javascript" if request.GET.first("type", "classic") == "classic" else "module"
+  inlineOrExternal = request.GET.first(b"inlineOrExternal", b"null")
+  hasBlockingStylesheet = request.GET.first(b"hasBlockingStylesheet", b"true") == b"true"
+  result = request.GET.first(b"result", b"success")
+  type = u"text/javascript" if request.GET.first(b"type", b"classic") == b"classic" else u"module"
 
-  response.headers.set("Content-Type", "text/html; charset=utf-8")
-  response.headers.set("Transfer-Encoding", "chunked")
+  response.headers.set(b"Content-Type", b"text/html; charset=utf-8")
+  response.headers.set(b"Transfer-Encoding", b"chunked")
   response.write_status_headers()
 
   # Step 1: Start parsing.
-  body = """<!DOCTYPE html>
+  body = u"""<!DOCTYPE html>
     <head>
       <script>
         parent.postMessage("fox", "*");
@@ -24,33 +27,33 @@ def main(request, response):
   """
 
   if hasBlockingStylesheet:
-    body += """
+    body += u"""
         <link rel="stylesheet" href="slow-flag-setter.py?result=css&cache=%f">
       """ % random.random()
 
-  body += """
+  body += u"""
     </head>
     <body>
   """
 
-  if inlineOrExternal == "inline" or inlineOrExternal == "external" or inlineOrExternal == "empty-src":
-    body += """
+  if inlineOrExternal == b"inline" or inlineOrExternal == b"external" or inlineOrExternal == b"empty-src":
+        body += u"""
       <streaming-element>
     """
 
   # Trigger DOM processing
-  body += "A" * 100000
+  body += u"A" * 100000
 
-  response.writer.write("%x\r\n" % len(body))
+  response.writer.write(u"%x\r\n" % len(body))
   response.writer.write(body)
-  response.writer.write("\r\n")
+  response.writer.write(u"\r\n")
   response.writer.flush()
 
-  body = ""
+  body = u""
 
-  if inlineOrExternal == "inline":
+  if inlineOrExternal == b"inline":
     time.sleep(1)
-    body += """
+    body += u"""
         <script id="s1" type="%s"
                 onload="scriptOnLoad()"
                 onerror="scriptOnError(event)">
@@ -59,26 +62,26 @@ def main(request, response):
         } else {
           window.didExecute = "executed";
         }
-    """ % (type)
-    if result == "parse-error":
-      body += "1=2 parse error\n"
+    """ % type
+    if result == b"parse-error":
+      body += u"1=2 parse error\n"
 
-    body += """
+    body += u"""
         </script>
       </streaming-element>
     """
-  elif inlineOrExternal == "external":
+  elif inlineOrExternal == b"external":
     time.sleep(1)
-    body += """
+    body += u"""
         <script id="s1" type="%s"
                 src="slow-flag-setter.py?result=%s&cache=%s"
                 onload="scriptOnLoad()"
                 onerror="scriptOnError(event)"></script>
       </streaming-element>
-    """ % (type, result, random.random())
-  elif inlineOrExternal == "empty-src":
+    """ % (type, isomorphic_decode(result), random.random())
+  elif inlineOrExternal == b"empty-src":
     time.sleep(1)
-    body += """
+    body += u"""
         <script id="s1" type="%s"
                 src=""
                 onload="scriptOnLoad()"
@@ -90,12 +93,12 @@ def main(request, response):
   #       // wasn't blocked by stylesheets as expected.
 
   # Trigger DOM processing
-  body += "B" * 100000
+  body += u"B" * 100000
 
-  response.writer.write("%x\r\n" % len(body))
+  response.writer.write(u"%x\r\n" % len(body))
   response.writer.write(body)
-  response.writer.write("\r\n")
+  response.writer.write(u"\r\n")
 
-  response.writer.write("0\r\n")
-  response.writer.write("\r\n")
+  response.writer.write(u"0\r\n")
+  response.writer.write(u"\r\n")
   response.writer.flush()
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/moving-between-documents/resources/slow-flag-setter.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/moving-between-documents/resources/slow-flag-setter.py
index 5b1872a8c99..20d7ed4bd0d 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/moving-between-documents/resources/slow-flag-setter.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/moving-between-documents/resources/slow-flag-setter.py
@@ -2,17 +2,17 @@
 import time
 
 def main(request, response):
-  headers = [("Content-Type", "text/javascript")]
+  headers = [(b"Content-Type", b"text/javascript")]
 
-  result = request.GET.first("result", "success")
-  if result == "css":
+  result = request.GET.first(b"result", b"success")
+  if result == b"css":
     time.sleep(3)
-    headers = [("Content-Type", "text/css")]
-    body = ""
+    headers = [(b"Content-Type", b"text/css")]
+    body = u""
   else:
     time.sleep(2)
 
-    body = """
+    body = u"""
       fetch('exec');
       console.log('exec');
       if (!window.readyToEvaluate) {
@@ -21,9 +21,9 @@ def main(request, response):
         window.didExecute = "executed";
       }
     """
-    if result == "parse-error":
-      body = "1=2 parse error;"
-    if result == "fetch-error":
-      return 404, [('Content-Type', 'text/plain')], """window.didExecute = "fetch error";"""
+    if result == b"parse-error":
+      body = u"1=2 parse error;"
+    if result == b"fetch-error":
+      return 404, [(b'Content-Type', b'text/plain')], u"""window.didExecute = "fetch error";"""
 
   return headers, body
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/resources/cross-origin.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/resources/cross-origin.py
index c319119ffd3..abac1901b7d 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/resources/cross-origin.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/resources/cross-origin.py
@@ -1,20 +1,20 @@
 def main(request, response):
-    origin = request.headers.get("origin")
+    origin = request.headers.get(b"origin")
 
     if origin is not None:
-        response.headers.set("Access-Control-Allow-Origin", origin)
-        response.headers.set("Access-Control-Allow-Methods", "GET")
-        response.headers.set("Access-Control-Allow-Credentials", "true")
+        response.headers.set(b"Access-Control-Allow-Origin", origin)
+        response.headers.set(b"Access-Control-Allow-Methods", b"GET")
+        response.headers.set(b"Access-Control-Allow-Credentials", b"true")
 
-    if request.method == "OPTIONS":
-        return ""
+    if request.method == u"OPTIONS":
+        return u""
 
-    headers = [("Content-Type", "text/javascript")]
-    milk = request.cookies.first("milk", None)
+    headers = [(b"Content-Type", b"text/javascript")]
+    milk = request.cookies.first(b"milk", None)
 
     if milk is None:
-        return headers, "var included = false;"
-    elif milk.value == "yes":
-        return headers, "var included = true;"
+        return headers, u"var included = false;"
+    elif milk.value == b"yes":
+        return headers, u"var included = true;"
 
-    return headers, "var included = false;"
+    return headers, u"var included = false;"
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/resources/load-error-events.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/resources/load-error-events.py
index 8599087be5e..1eb82cd497d 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/resources/load-error-events.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/resources/load-error-events.py
@@ -1,15 +1,15 @@
 import re
 
 def main(request, response):
-    headers = [("Content-Type", "text/javascript")]
-    test = request.GET.first('test')
-    assert(re.match('^[a-zA-Z0-9_]+$', test));
+    headers = [(b"Content-Type", b"text/javascript")]
+    test = request.GET.first(b'test')
+    assert(re.match(b'^[a-zA-Z0-9_]+$', test))
 
-    if test.find('_load') >= 0:
+    if test.find(b'_load') >= 0:
       status = 200
-      content = '"use strict"; %s.executed = true;' % test
+      content = b'"use strict"; %s.executed = true;' % test
     else:
       status = 404
-      content = '"use strict"; %s.test.step(function() { assert_unreached("404 script should not be executed"); });' % test
+      content = b'"use strict"; %s.test.step(function() { assert_unreached("404 script should not be executed"); });' % test
 
     return status, headers, content
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/script-not-found-not-executed-2.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/script-not-found-not-executed-2.py
index 53caed7c043..4ff5be7374d 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/script-not-found-not-executed-2.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/script-not-found-not-executed-2.py
@@ -1,4 +1,4 @@
 def main(request, response):
-    headers = [("Content-Type", "text/javascript")]
-    body = "test2_token = \"script executed\";"
+    headers = [(b"Content-Type", b"text/javascript")]
+    body = u"test2_token = \"script executed\";"
     return 200, headers, body
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/script-not-found-not-executed.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/script-not-found-not-executed.py
index 7722bd3f231..9354d427030 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/script-not-found-not-executed.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/script-not-found-not-executed.py
@@ -1,4 +1,4 @@
 def main(request, response):
-    headers = [("Content-Type", "text/javascript")]
-    body = "test1_token = \"script executed\";"
+    headers = [(b"Content-Type", b"text/javascript")]
+    body = u"test1_token = \"script executed\";"
     return 404, headers, body
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/serve-with-content-type.py b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/serve-with-content-type.py
index 7cfe6f4cec3..675b3fc3eb0 100644
--- a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/serve-with-content-type.py
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/serve-with-content-type.py
@@ -1,15 +1,17 @@
 import os
 
+from wptserve.utils import isomorphic_decode
+
 def main(request, response):
-    directory = os.path.dirname(__file__)
+    directory = os.path.dirname(isomorphic_decode(__file__))
 
     try:
-        file_name = request.GET.first("fn")
-        content_type = request.GET.first("ct")
-        with open(os.path.join(directory, file_name), "rb") as fh:
+        file_name = request.GET.first(b"fn")
+        content_type = request.GET.first(b"ct")
+        with open(os.path.join(directory, isomorphic_decode(file_name)), u"rb") as fh:
             content = fh.read()
 
-        response.headers.set("Content-Type", content_type)
+        response.headers.set(b"Content-Type", content_type)
         response.content = content
     except:
-        response.set_error(400, "Not enough parameters or file not found")
+        response.set_error(400, u"Not enough parameters or file not found")
diff --git a/tests/wpt/web-platform-tests/lifecycle/resources/beacon.py b/tests/wpt/web-platform-tests/lifecycle/resources/beacon.py
index 8718b84386b..09915ffbcf0 100644
--- a/tests/wpt/web-platform-tests/lifecycle/resources/beacon.py
+++ b/tests/wpt/web-platform-tests/lifecycle/resources/beacon.py
@@ -6,8 +6,8 @@ def main(request, response):
     # |query| should be a request parameter indicating the request would like
     # to know how many times the server has seen the request (with the
     # same token).
-    token = request.GET.first("token", None)
-    is_query = request.GET.first("query", None) is not None
+    token = request.GET.first(b"token", None)
+    is_query = request.GET.first(b"query", None) is not None
     with request.server.stash.lock:
       value = request.server.stash.take(token)
       count = 0
@@ -21,5 +21,5 @@ def main(request, response):
 
     headers = []
     if is_query:
-      headers = [("Count", count)]
-    return (200, headers, "")
+      headers = [(b"Count", count)]
+    return (200, headers, b"")
diff --git a/tests/wpt/web-platform-tests/mimesniff/mime-types/resources/mime-charset.py b/tests/wpt/web-platform-tests/mimesniff/mime-types/resources/mime-charset.py
index a4f90f52c32..46d8252e0c9 100644
--- a/tests/wpt/web-platform-tests/mimesniff/mime-types/resources/mime-charset.py
+++ b/tests/wpt/web-platform-tests/mimesniff/mime-types/resources/mime-charset.py
@@ -1,5 +1,7 @@
+from wptserve.utils import isomorphic_encode
+
 def main(request, response):
-    content = "<meta charset=utf-8>\n<script>document.write(document.characterSet)</script>"
+    content = b"<meta charset=utf-8>\n<script>document.write(document.characterSet)</script>"
 
     # This uses the following rather than
     #   response.headers.set("Content-Type", request.GET.first("type"));
@@ -7,10 +9,10 @@ def main(request, response):
     # to work around https://github.com/web-platform-tests/wpt/issues/8372.
 
     response.add_required_headers = False
-    output =  "HTTP/1.1 200 OK\r\n"
-    output += "Content-Length: " + str(len(content)) + "\r\n"
-    output += "Content-Type: " + request.GET.first("type") + "\r\n"
-    output += "\r\n"
+    output = b"HTTP/1.1 200 OK\r\n"
+    output += b"Content-Length: " + isomorphic_encode(str(len(content))) + b"\r\n"
+    output += b"Content-Type: " + request.GET.first(b"type") + b"\r\n"
+    output += b"\r\n"
     output += content
     response.writer.write(output)
     response.close_connection = True
diff --git a/tests/wpt/web-platform-tests/network-error-logging/support/cached-with-validation.py b/tests/wpt/web-platform-tests/network-error-logging/support/cached-with-validation.py
index f98a503a51e..e5090e03929 100644
--- a/tests/wpt/web-platform-tests/network-error-logging/support/cached-with-validation.py
+++ b/tests/wpt/web-platform-tests/network-error-logging/support/cached-with-validation.py
@@ -1,17 +1,17 @@
-ETAG = '"123abc"'
-CONTENT_TYPE = "text/plain"
-CONTENT = "lorem ipsum dolor sit amet"
+ETAG = b'"123abc"'
+CONTENT_TYPE = b"text/plain"
+CONTENT = u"lorem ipsum dolor sit amet"
 
 def main(request, response):
     # let caching kick in if possible (conditional GET)
-    etag = request.headers.get("If-None-Match", None)
+    etag = request.headers.get(b"If-None-Match", None)
     if etag == ETAG:
-        response.headers.set("X-HTTP-STATUS", 304)
-        response.status = (304, "Not Modified")
-        return ""
+        response.headers.set(b"X-HTTP-STATUS", 304)
+        response.status = (304, b"Not Modified")
+        return u""
 
     # cache miss, so respond with the actual content
-    response.status = (200, "OK")
-    response.headers.set("ETag", ETAG)
-    response.headers.set("Content-Type", CONTENT_TYPE)
+    response.status = (200, b"OK")
+    response.headers.set(b"ETag", ETAG)
+    response.headers.set(b"Content-Type", CONTENT_TYPE)
     return CONTENT
diff --git a/tests/wpt/web-platform-tests/network-error-logging/support/lock.py b/tests/wpt/web-platform-tests/network-error-logging/support/lock.py
index 48d99abbaf7..0c5ae6b6f5d 100644
--- a/tests/wpt/web-platform-tests/network-error-logging/support/lock.py
+++ b/tests/wpt/web-platform-tests/network-error-logging/support/lock.py
@@ -8,7 +8,7 @@
 
 import time
 
-_LOCK_KEY = "67966d2e-a847-41d8-b7c3-5f6aee3375ba"
+_LOCK_KEY = b"67966d2e-a847-41d8-b7c3-5f6aee3375ba"
 _TIMEOUT = 5  # seconds
 
 def wait_for_lock(request):
@@ -24,9 +24,9 @@ def lock(request, report_id):
   with request.server.stash.lock:
     # Loop until the lock is free
     if not wait_for_lock(request):
-      return (503, [], "Cannot obtain lock")
+      return (503, [], b"Cannot obtain lock")
     request.server.stash.put(key=_LOCK_KEY, value=report_id)
-    return "Obtained lock for %s" % report_id
+    return b"Obtained lock for %s" % report_id
 
 def unlock(request, report_id):
   with request.server.stash.lock:
@@ -34,15 +34,15 @@ def unlock(request, report_id):
     if lock_holder != report_id:
       # Return the lock holder to the stash
       request.server.stash.put(key=_LOCK_KEY, value=lock_holder)
-      return (503, [], "Cannot release lock held by %s" % lock_holder)
-  return "Released lock for %s" % report_id
+      return (503, [], b"Cannot release lock held by %s" % lock_holder)
+  return b"Released lock for %s" % report_id
 
 def main(request, response):
-  op = request.GET.first("op")
-  report_id = request.GET.first("reportID")
-  if op == "lock":
+  op = request.GET.first(b"op")
+  report_id = request.GET.first(b"reportID")
+  if op == b"lock":
     return lock(request, report_id)
-  elif op == "unlock":
+  elif op == b"unlock":
     return unlock(request, report_id)
   else:
-    return (400, [], "Invalid op")
+    return (400, [], b"Invalid op")
diff --git a/tests/wpt/web-platform-tests/network-error-logging/support/redirect.py b/tests/wpt/web-platform-tests/network-error-logging/support/redirect.py
index 00813504da6..7da45047643 100644
--- a/tests/wpt/web-platform-tests/network-error-logging/support/redirect.py
+++ b/tests/wpt/web-platform-tests/network-error-logging/support/redirect.py
@@ -1,3 +1,3 @@
 # Always redirects to no-policy-pass.png.
 def main(request, response):
-  return 302, [("Location", "no-policy-pass.png")], ""
+  return 302, [(b"Location", b"no-policy-pass.png")], u""
diff --git a/tests/wpt/web-platform-tests/network-error-logging/support/report.py b/tests/wpt/web-platform-tests/network-error-logging/support/report.py
index 4bb7e3d248b..671b3a28921 100644
--- a/tests/wpt/web-platform-tests/network-error-logging/support/report.py
+++ b/tests/wpt/web-platform-tests/network-error-logging/support/report.py
@@ -15,36 +15,36 @@ def retrieve_from_stash(request, key, timeout, min_count, default_value):
 
 def main(request, response):
   # Handle CORS preflight requests
-  if request.method == 'OPTIONS':
+  if request.method == u'OPTIONS':
     # Always reject preflights for one subdomain
-    if "www2" in request.headers["Origin"]:
-      return (400, [], "CORS preflight rejected for www2")
+    if b"www2" in request.headers[b"Origin"]:
+      return (400, [], u"CORS preflight rejected for www2")
     return [
-      ("Content-Type", "text/plain"),
-      ("Access-Control-Allow-Origin", "*"),
-      ("Access-Control-Allow-Methods", "post"),
-      ("Access-Control-Allow-Headers", "Content-Type"),
-    ], "CORS allowed"
+      (b"Content-Type", b"text/plain"),
+      (b"Access-Control-Allow-Origin", b"*"),
+      (b"Access-Control-Allow-Methods", b"post"),
+      (b"Access-Control-Allow-Headers", b"Content-Type"),
+    ], u"CORS allowed"
 
-  op = request.GET.first("op");
-  key = request.GET.first("reportID")
+  op = request.GET.first(b"op");
+  key = request.GET.first(b"reportID")
 
-  if op == "retrieve_report":
+  if op == b"retrieve_report":
     try:
-      timeout = float(request.GET.first("timeout"))
+      timeout = float(request.GET.first(b"timeout"))
     except:
       timeout = 0.5
     try:
-      min_count = int(request.GET.first("min_count"))
+      min_count = int(request.GET.first(b"min_count"))
     except:
       min_count = 1
-    return [("Content-Type", "application/json")], retrieve_from_stash(request, key, timeout, min_count, '[]')
+    return [(b"Content-Type", b"application/json")], retrieve_from_stash(request, key, timeout, min_count, u'[]')
 
   # append new reports
   new_reports = json.loads(request.body)
   for report in new_reports:
-    report["metadata"] = {
-      "content_type": request.headers["Content-Type"],
+    report[u"metadata"] = {
+      b"content_type": request.headers[b"Content-Type"],
     }
   with request.server.stash.lock:
     reports = request.server.stash.take(key=key)
@@ -54,4 +54,4 @@ def main(request, response):
     request.server.stash.put(key=key, value=reports)
 
   # return acknowledgement report
-  return [("Content-Type", "text/plain")], "Recorded report"
+  return [(b"Content-Type", b"text/plain")], u"Recorded report"
diff --git a/tests/wpt/web-platform-tests/origin-isolation/about-blank.https.sub.html b/tests/wpt/web-platform-tests/origin-isolation/about-blank.https.sub.html
index ec24853a160..50a07ff0c02 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/about-blank.https.sub.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/about-blank.https.sub.html
@@ -11,7 +11,8 @@ import {
   insertIframe,
   setBothDocumentDomains,
   testSameAgentCluster,
-  testDifferentAgentClusters
+  testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -25,6 +26,10 @@ testSameAgentCluster([self, 0], "parent to about:blank");
 testDifferentAgentClusters([0, 1], "about:blank to child2");
 testDifferentAgentClusters([1, 0], "child2 to about:blank");
 
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, true, "about:blank");
+testOriginIsolationRestricted(1, false, "child2");
+
 async function insertAboutBlankIframe() {
   const iframe = document.createElement("iframe");
   document.body.append(iframe);
diff --git a/tests/wpt/web-platform-tests/origin-isolation/getter-data-url.https.html b/tests/wpt/web-platform-tests/origin-isolation/getter-data-url.https.html
new file mode 100644
index 00000000000..da2c87b1270
--- /dev/null
+++ b/tests/wpt/web-platform-tests/origin-isolation/getter-data-url.https.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>window.originIsolationRestricted for a data: URL</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<div id="log"></div>
+
+<script type="module">
+import {
+  waitForIframe,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
+
+promise_setup(() => {
+  const iframe = document.createElement("iframe");
+
+  // This copies parts of resources/send-origin-isolation-header.py that allow
+  // us to reuse testOriginIsolationRestricted.
+  iframe.src = `data:text/html,<script>
+    window.onmessage = () => {
+      parent.postMessage(self.originIsolationRestricted, "*");
+    };
+    </` + `script>
+  `;
+
+  const waitPromise = waitForIframe(iframe);
+  document.body.append(iframe);
+  return waitPromise;
+});
+
+// The data: URL iframe has an opaque origin, so it definitely should return
+// false. It's pretty unlikely that it would return true anyway, since we can't
+// set the header on the iframe, but we should test it to make sure there isn't
+// some strange main page -> data: URL iframe inheritance going on.
+
+testOriginIsolationRestricted(0, false);
+</script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/getter-data-url.https.html.headers b/tests/wpt/web-platform-tests/origin-isolation/getter-data-url.https.html.headers
new file mode 100644
index 00000000000..ea3f6b335c7
--- /dev/null
+++ b/tests/wpt/web-platform-tests/origin-isolation/getter-data-url.https.html.headers
@@ -0,0 +1 @@
+Origin-Isolation: ?1
diff --git a/tests/wpt/web-platform-tests/origin-isolation/getter-removed-iframe.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/getter-removed-iframe.sub.https.html
new file mode 100644
index 00000000000..a1373468e22
--- /dev/null
+++ b/tests/wpt/web-platform-tests/origin-isolation/getter-removed-iframe.sub.https.html
@@ -0,0 +1,27 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>window.crossOriginIsolated for a removed frame</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<div id="log"></div>
+
+<script type="module">
+import { navigateIframe } from "./resources/helpers.mjs";
+
+promise_test(async () => {
+  // We cannot use insertIframe because it sets both `document.domain`s. That
+  // shouldn't matter, but Chrome has a bug (https://crbug.com/1095145), so
+  // let's avoid making the test needlessly fail because of that bug.
+  const iframe = document.createElement("iframe");
+  const navigatePromise = navigateIframe(iframe, "{{hosts[][]}}", "?1");
+  document.body.append(iframe);
+  await navigatePromise;
+
+  const frameWindow = iframe.contentWindow;
+
+  assert_equals(frameWindow.originIsolationRestricted, true, "before");
+  iframe.remove();
+  assert_equals(frameWindow.originIsolationRestricted, true, "after");
+}, "Removing the iframe does not change originIsolationRestricted");
+</script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/getter-removed-iframe.sub.https.html.headers b/tests/wpt/web-platform-tests/origin-isolation/getter-removed-iframe.sub.https.html.headers
new file mode 100644
index 00000000000..ea3f6b335c7
--- /dev/null
+++ b/tests/wpt/web-platform-tests/origin-isolation/getter-removed-iframe.sub.https.html.headers
@@ -0,0 +1 @@
+Origin-Isolation: ?1
diff --git a/tests/wpt/web-platform-tests/origin-isolation/getter-sandboxed-iframe.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/getter-sandboxed-iframe.sub.https.html
new file mode 100644
index 00000000000..366fae6e5e9
--- /dev/null
+++ b/tests/wpt/web-platform-tests/origin-isolation/getter-sandboxed-iframe.sub.https.html
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>window.originIsolationRestricted for a sandboxed frame</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<div id="log"></div>
+
+<script type="module">
+import {
+  navigateIframe,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
+
+// We do this manually instead of using insertIframe because we want to add a
+// sandbox="" attribute and we don't want to set both document.domains.
+promise_setup(() => {
+  const iframe = document.createElement("iframe");
+  iframe.sandbox = "allow-scripts";
+  const navigatePromise = navigateIframe(iframe, "{{hosts[][]}}", "?1");
+  document.body.append(iframe);
+  return navigatePromise;
+});
+
+// Because sandboxed iframes have an opaque origin, their agent cluster key is
+// always an origin, so there are no additional restrictions imposed by origin
+// isolation. Thus the getter returns false.
+
+testOriginIsolationRestricted(0, false);
+</script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/getter-sandboxed-iframe.sub.https.html.headers b/tests/wpt/web-platform-tests/origin-isolation/getter-sandboxed-iframe.sub.https.html.headers
new file mode 100644
index 00000000000..ea3f6b335c7
--- /dev/null
+++ b/tests/wpt/web-platform-tests/origin-isolation/getter-sandboxed-iframe.sub.https.html.headers
@@ -0,0 +1 @@
+Origin-Isolation: ?1
diff --git a/tests/wpt/web-platform-tests/origin-isolation/insecure-http.sub.html b/tests/wpt/web-platform-tests/origin-isolation/insecure-http.sub.html
index 1e78b133857..83df16af455 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/insecure-http.sub.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/insecure-http.sub.html
@@ -16,4 +16,9 @@ promise_setup(async () => {
 // All isolation requests are ignored, since this is over insecure HTTP.
 // So both end up in the site-keyed agent cluster.
 testSameAgentCluster([self, 0]);
+
+// Has to be promise_test because we used promise_setup().
+promise_test(async () => {
+  assert_false("originIsolationRestricted" in window);
+}, "The getter must not exist");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-bad-subdomain.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-bad-subdomain.sub.https.html
index ae55f5d83e1..cfa39aaee03 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-bad-subdomain.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-bad-subdomain.sub.https.html
@@ -7,7 +7,11 @@
 <div id="log"></div>
 
 <script type="module">
-import { insertIframe, testSameAgentCluster } from "./resources/helpers.mjs";
+import {
+  insertIframe,
+  testSameAgentCluster,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
 
 let frameIndex = 0;
 for (const badValue of ["", "?0", "true", "\"?1\"", "1", "?2", "(?1)"]) {
@@ -17,6 +21,7 @@ for (const badValue of ["", "?0", "true", "\"?1\"", "1", "?2", "(?1)"]) {
 
   // Since the header values are bad there should be no isolation
   testSameAgentCluster([self, frameIndex], `"${badValue}"`);
+  testOriginIsolationRestricted(frameIndex, false, `"${badValue}"`);
   ++frameIndex;
 }
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-same.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-same.sub.https.html
index 8e32649d3a2..ece3b9732a5 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-same.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-same.sub.https.html
@@ -7,7 +7,11 @@
 <div id="log"></div>
 
 <script type="module">
-import { insertIframe, testSameAgentCluster } from "./resources/helpers.mjs";
+import {
+  insertIframe,
+  testSameAgentCluster,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
 
 promise_setup(async () => {
   await insertIframe("{{hosts[][]}}", "?1");
@@ -16,4 +20,6 @@ promise_setup(async () => {
 // Since they're same-origin, and the parent loaded without isolation, the
 // child's request for isolation gets ignored, and both end up site-keyed.
 testSameAgentCluster([self, 0]);
+testOriginIsolationRestricted(self, false, "parent");
+testOriginIsolationRestricted(0, false, "child");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-subdomain.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-subdomain.sub.https.html
index 7f4a9413e35..ab060e24f49 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-subdomain.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-subdomain.sub.https.html
@@ -7,7 +7,11 @@
 <div id="log"></div>
 
 <script type="module">
-import { insertIframe, testDifferentAgentClusters } from "./resources/helpers.mjs";
+import {
+  insertIframe,
+  testDifferentAgentClusters,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
 
 promise_setup(async () => {
   await insertIframe("{{hosts[][www]}}", "?1");
@@ -17,4 +21,6 @@ promise_setup(async () => {
 // so the parent ends up in the site-keyed agent cluster and the child in the
 // origin-keyed one.
 testDifferentAgentClusters([self, 0]);
+testOriginIsolationRestricted(self, false, "parent");
+testOriginIsolationRestricted(0, true, "child");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-with-params-subdomain.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-with-params-subdomain.sub.https.html
index 0208ac3e14c..e1459b9cc08 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-with-params-subdomain.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child-yes-with-params-subdomain.sub.https.html
@@ -7,7 +7,11 @@
 <div id="log"></div>
 
 <script type="module">
-import { insertIframe, testDifferentAgentClusters } from "./resources/helpers.mjs";
+import {
+  insertIframe,
+  testDifferentAgentClusters,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
 
 promise_setup(async () => {
   await insertIframe("{{hosts[][www]}}", "?1;param1;param2=value2");
@@ -17,4 +21,6 @@ promise_setup(async () => {
 // so the parent ends up in the site-keyed agent cluster and the child in the
 // origin-keyed one.
 testDifferentAgentClusters([self, 0]);
+testOriginIsolationRestricted(self, false, "parent");
+testOriginIsolationRestricted(0, true, "child");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-no-child2-yes-children-different.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-no-child2-yes-children-different.sub.https.html
index c019ef2fe7d..17ee8a678a6 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-no-child2-yes-children-different.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-no-child2-yes-children-different.sub.https.html
@@ -11,6 +11,7 @@ import {
   insertIframe,
   testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -30,4 +31,8 @@ testSameAgentCluster([self, 0], "Parent to child1");
 testDifferentAgentClusters([self, 1], "Parent to child2");
 testDifferentAgentClusters([0, 1], "child1 to child2");
 testDifferentAgentClusters([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, false, "parent");
+testOriginIsolationRestricted(0, false, "child1");
+testOriginIsolationRestricted(1, true, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-no-child2-yes-children-same.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-no-child2-yes-children-same.sub.https.html
index 9ca18f8941b..17b82bc09df 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-no-child2-yes-children-same.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-no-child2-yes-children-same.sub.https.html
@@ -7,7 +7,11 @@
 <div id="log"></div>
 
 <script type="module">
-import { insertIframe, testSameAgentCluster } from "./resources/helpers.mjs";
+import {
+  insertIframe,
+  testSameAgentCluster,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
 
 promise_setup(async () => {
   // Must be sequential, not parallel: the non-isolated frame must load first.
@@ -25,4 +29,8 @@ testSameAgentCluster([self, 0], "Parent to child1");
 testSameAgentCluster([self, 1], "Parent to child2");
 testSameAgentCluster([0, 1], "child1 to child2");
 testSameAgentCluster([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, false, "parent");
+testOriginIsolationRestricted(0, false, "child1");
+testOriginIsolationRestricted(1, false, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-yes-child2-no-children-same.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-yes-child2-no-children-same.sub.https.html
index 2947e629bd5..f6955c55c25 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-yes-child2-no-children-same.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-no-child1-yes-child2-no-children-same.sub.https.html
@@ -11,6 +11,7 @@ import {
   insertIframe,
   testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -30,4 +31,8 @@ testDifferentAgentClusters([self, 0], "Parent to child1");
 testDifferentAgentClusters([self, 1], "Parent to child2");
 testSameAgentCluster([0, 1], "child1 to child2");
 testSameAgentCluster([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, false, "parent");
+testOriginIsolationRestricted(0, true, "child1");
+testOriginIsolationRestricted(1, true, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-no-same.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-no-same.sub.https.html
index aa1dd94682e..7edebe9bd88 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-no-same.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-no-same.sub.https.html
@@ -7,7 +7,11 @@
 <div id="log"></div>
 
 <script type="module">
-import { insertIframe, testSameAgentCluster } from "./resources/helpers.mjs";
+import {
+  insertIframe,
+  testSameAgentCluster,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
 
 promise_setup(async () => {
   await insertIframe("{{hosts[][]}}");
@@ -16,4 +20,7 @@ promise_setup(async () => {
 // Since they're same-origin, and the parent loaded with isolation, the
 // child's non-request for isolation gets ignored, and both end up origin-keyed.
 testSameAgentCluster([self, 0]);
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, true, "child");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-no-subdomain.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-no-subdomain.sub.https.html
index 5055d295d03..f0cd3c48113 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-no-subdomain.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-no-subdomain.sub.https.html
@@ -7,7 +7,11 @@
 <div id="log"></div>
 
 <script type="module">
-import { insertIframe, testDifferentAgentClusters } from "./resources/helpers.mjs";
+import {
+  insertIframe,
+  testDifferentAgentClusters,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
 
 promise_setup(async () => {
   await insertIframe("{{hosts[][www]}}");
@@ -17,4 +21,7 @@ promise_setup(async () => {
 // as is the child's non-request. So the parent ends up in the origin-keyed
 // agent cluster and the child ends up in the site-keyed one.
 testDifferentAgentClusters([self, 0]);
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, false, "child");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-yes-same.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-yes-same.sub.https.html
index 3d99486a3cb..c4917819617 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-yes-same.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-yes-same.sub.https.html
@@ -7,7 +7,11 @@
 <div id="log"></div>
 
 <script type="module">
-import { insertIframe, testSameAgentCluster } from "./resources/helpers.mjs";
+import {
+  insertIframe,
+  testSameAgentCluster,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
 
 promise_setup(async () => {
   await insertIframe("{{hosts[][]}}", "?1");
@@ -16,4 +20,7 @@ promise_setup(async () => {
 // Both request isolation, and they're same-origin, so they both end up in the
 // same origin-keyed agent cluster.
 testSameAgentCluster([self, 0]);
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, true, "child");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-yes-subdomain.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-yes-subdomain.sub.https.html
index afc8f5b2acd..fc5b19843cb 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-yes-subdomain.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child-yes-subdomain.sub.https.html
@@ -7,7 +7,11 @@
 <div id="log"></div>
 
 <script type="module">
-import { insertIframe, testDifferentAgentClusters } from "./resources/helpers.mjs";
+import {
+  insertIframe,
+  testDifferentAgentClusters,
+  testOriginIsolationRestricted
+} from "./resources/helpers.mjs";
 
 promise_setup(async () => {
   await insertIframe("{{hosts[][www]}}", "?1");
@@ -17,4 +21,7 @@ promise_setup(async () => {
 // cluster (the base domain's origin), and the child ends up in a different
 // origin-keyed agent cluster (the www subdomain's origin).
 testDifferentAgentClusters([self, 0]);
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, true, "child");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-no-children-different.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-no-children-different.sub.https.html
index 77a77d50a1c..1635bd63848 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-no-children-different.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-no-children-different.sub.https.html
@@ -11,6 +11,7 @@ import {
   insertIframe,
   testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -30,4 +31,8 @@ testDifferentAgentClusters([self, 0], "Parent to child1");
 testDifferentAgentClusters([self, 1], "Parent to child2");
 testSameAgentCluster([0, 1], "child1 to child2");
 testSameAgentCluster([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, false, "child1");
+testOriginIsolationRestricted(1, false, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-no-children-same.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-no-children-same.sub.https.html
index b3f18e8560f..0f2f29025e7 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-no-children-same.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-no-children-same.sub.https.html
@@ -11,6 +11,7 @@ import {
   insertIframe,
   testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -30,4 +31,8 @@ testDifferentAgentClusters([self, 0], "Parent to child1");
 testDifferentAgentClusters([self, 1], "Parent to child2");
 testSameAgentCluster([0, 1], "child1 to child2");
 testSameAgentCluster([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, false, "child1");
+testOriginIsolationRestricted(1, false, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-yes-children-different.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-yes-children-different.sub.https.html
index 8e7b4d3ee5c..c830e1548c0 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-yes-children-different.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-yes-children-different.sub.https.html
@@ -9,8 +9,8 @@
 <script type="module">
 import {
   insertIframe,
-  testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -31,4 +31,8 @@ testDifferentAgentClusters([self, 0], "Parent to child1");
 testDifferentAgentClusters([self, 1], "Parent to child2");
 testDifferentAgentClusters([0, 1], "child1 to child2");
 testDifferentAgentClusters([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, false, "child1");
+testOriginIsolationRestricted(1, true, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-yes-children-same.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-yes-children-same.sub.https.html
index 260ac80d2ff..dc157a9eef9 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-yes-children-same.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-no-child2-yes-children-same.sub.https.html
@@ -11,6 +11,7 @@ import {
   insertIframe,
   testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -30,4 +31,8 @@ testDifferentAgentClusters([self, 0], "Parent to child1");
 testDifferentAgentClusters([self, 1], "Parent to child2");
 testSameAgentCluster([0, 1], "child1 to child2");
 testSameAgentCluster([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, false, "child1");
+testOriginIsolationRestricted(1, false, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-no-children-same.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-no-children-same.sub.https.html
index ae54fcd02ea..033fdd2827f 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-no-children-same.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-no-children-same.sub.https.html
@@ -11,6 +11,7 @@ import {
   insertIframe,
   testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -30,4 +31,8 @@ testDifferentAgentClusters([self, 0], "Parent to child1");
 testDifferentAgentClusters([self, 1], "Parent to child2");
 testSameAgentCluster([0, 1], "child1 to child2");
 testSameAgentCluster([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, true, "child1");
+testOriginIsolationRestricted(1, true, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-yes-children-different.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-yes-children-different.sub.https.html
index 775f753561b..2c1f1341df5 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-yes-children-different.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-yes-children-different.sub.https.html
@@ -9,8 +9,8 @@
 <script type="module">
 import {
   insertIframe,
-  testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -31,4 +31,8 @@ testDifferentAgentClusters([self, 0], "Parent to child1");
 testDifferentAgentClusters([self, 1], "Parent to child2");
 testDifferentAgentClusters([0, 1], "child1 to child2");
 testDifferentAgentClusters([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, true, "child1");
+testOriginIsolationRestricted(1, true, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-yes-children-same.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-yes-children-same.sub.https.html
index a3b0939862c..2de08307fcb 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-yes-children-same.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/parent-yes-child1-yes-child2-yes-children-same.sub.https.html
@@ -11,6 +11,7 @@ import {
   insertIframe,
   testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 promise_setup(async () => {
@@ -31,4 +32,8 @@ testDifferentAgentClusters([self, 0], "Parent to child1");
 testDifferentAgentClusters([self, 1], "Parent to child2");
 testSameAgentCluster([0, 1], "child1 to child2");
 testSameAgentCluster([1, 0], "child2 to child1");
+
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, true, "child1");
+testOriginIsolationRestricted(1, true, "child2");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/removing-iframes.sub.https.html b/tests/wpt/web-platform-tests/origin-isolation/removing-iframes.sub.https.html
index 2f01562b04c..3a6d91c447a 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/removing-iframes.sub.https.html
+++ b/tests/wpt/web-platform-tests/origin-isolation/removing-iframes.sub.https.html
@@ -1,6 +1,6 @@
 <!DOCTYPE html>
 <meta charset="utf-8">
-<title>Parent is isolated, child1 is not isolated, child1 navigates to a different site, child2 gets inserted and is isolated, child1 navigates back</title>
+<title>A non-isolated child at a given origin causes future children to also be non-isolated even after the iframe is removed</title>
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 
@@ -11,6 +11,7 @@ import {
   insertIframe,
   testSameAgentCluster,
   testDifferentAgentClusters,
+  testOriginIsolationRestricted
 } from "./resources/helpers.mjs";
 
 let frame1;
@@ -22,6 +23,8 @@ promise_setup(async () => {
 // as is the child's non-request. So the parent ends up in the origin-keyed
 // agent cluster and the child ends up in the site-keyed one.
 testDifferentAgentClusters([self, 0], "Before");
+testOriginIsolationRestricted(self, true, "parent");
+testOriginIsolationRestricted(0, false, "child1");
 
 promise_test(async () => {
   frame1.remove();
@@ -37,4 +40,7 @@ testDifferentAgentClusters([self, 0], "Parent to child2");
 testDifferentAgentClusters([self, 1], "Parent to child3");
 testSameAgentCluster([0, 1], "child2 to child3");
 testSameAgentCluster([1, 0], "child3 to child2");
+
+testOriginIsolationRestricted(0, false, "child2");
+testOriginIsolationRestricted(1, false, "child3");
 </script>
diff --git a/tests/wpt/web-platform-tests/origin-isolation/resources/README.md b/tests/wpt/web-platform-tests/origin-isolation/resources/README.md
new file mode 100644
index 00000000000..dd5e192bcd5
--- /dev/null
+++ b/tests/wpt/web-platform-tests/origin-isolation/resources/README.md
@@ -0,0 +1,6 @@
+Why are there `.headers` files here for the `.mjs` scripts?
+
+Because `../getter-sandboxed-iframe.sub.https.html` is testing an opaque origin,
+which is cross-origin with these scripts. Since `<script type="module">`
+respects the same-origin policy, we need CORS headers to allow them to be
+accessed.
diff --git a/tests/wpt/web-platform-tests/origin-isolation/resources/child-frame-script.mjs b/tests/wpt/web-platform-tests/origin-isolation/resources/child-frame-script.mjs
index 038c0f3a848..2c6760a3e37 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/resources/child-frame-script.mjs
+++ b/tests/wpt/web-platform-tests/origin-isolation/resources/child-frame-script.mjs
@@ -30,6 +30,8 @@ window.onmessage = async (e) => {
     } catch (e) {
       parent.postMessage(e.name, "*");
     }
+  } else if (e.data.command === "get originIsolationRestricted") {
+    parent.postMessage(self.originIsolationRestricted, "*");
   }
 
   // We could also receive e.data === "WebAssembly.Module message received",
diff --git a/tests/wpt/web-platform-tests/origin-isolation/resources/child-frame-script.mjs.headers b/tests/wpt/web-platform-tests/origin-isolation/resources/child-frame-script.mjs.headers
new file mode 100644
index 00000000000..cb762eff806
--- /dev/null
+++ b/tests/wpt/web-platform-tests/origin-isolation/resources/child-frame-script.mjs.headers
@@ -0,0 +1 @@
+Access-Control-Allow-Origin: *
diff --git a/tests/wpt/web-platform-tests/origin-isolation/resources/helpers.mjs b/tests/wpt/web-platform-tests/origin-isolation/resources/helpers.mjs
index 8943707778c..50ca1ab4874 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/resources/helpers.mjs
+++ b/tests/wpt/web-platform-tests/origin-isolation/resources/helpers.mjs
@@ -158,6 +158,32 @@ export function testDifferentAgentClusters(testFrames, testLabelPrefix) {
   }
 }
 
+/**
+ * Creates a promise_test() to check the value of the originIsolationRestricted
+ * getter in the given testFrame.
+ * @param {Window|number} testFrame - Either self, or a frame index to test.
+ * @param {boolean} expected - The expected value for originIsolationRestricted.
+ * @param {string=} testLabelPrefix - A prefix used in the test names. This can
+ *   be omitted if the function is only used once in a test file.
+ */
+export function testOriginIsolationRestricted(testFrame, expected, testLabelPrefix) {
+  const prefix = testLabelPrefix === undefined ? "" : `${testLabelPrefix}: `;
+
+  if (testFrame === self) {
+    // Need to use promise_test() even though it's sync because we use
+    // promise_setup() in many tests.
+    promise_test(async () => {
+      assert_equals(self.originIsolationRestricted, expected);
+    }, `${prefix}originIsolationRestricted must equal ${expected}`);
+  } else {
+    promise_test(async () => {
+      const frameWindow = frames[testFrame];
+      const result = await getOriginIsolationRestricted(frameWindow);
+      assert_equals(result, expected);
+    }, `${prefix}originIsolationRestricted must equal ${expected}`);
+  }
+}
+
 /**
  * Sends a WebAssembly.Module instance to the given Window, and waits for it to
  * send back a message indicating whether it got the module or got a
@@ -197,6 +223,13 @@ export async function setBothDocumentDomains(frameWindow) {
   assert_equals(whatHappened, "document.domain is set");
 }
 
+async function getOriginIsolationRestricted(frameWindow) {
+  // This function is coupled to ./send-origin-isolation-header.py, which ensures
+  // that sending such a message will result in a message back.
+  frameWindow.postMessage({ command: "get originIsolationRestricted" }, "*");
+  return waitForMessage(frameWindow);
+}
+
 function getIframeURL(hostname, header) {
   const url = new URL("send-origin-isolation-header.py", import.meta.url);
   url.hostname = hostname;
diff --git a/tests/wpt/web-platform-tests/origin-isolation/resources/helpers.mjs.headers b/tests/wpt/web-platform-tests/origin-isolation/resources/helpers.mjs.headers
new file mode 100644
index 00000000000..cb762eff806
--- /dev/null
+++ b/tests/wpt/web-platform-tests/origin-isolation/resources/helpers.mjs.headers
@@ -0,0 +1 @@
+Access-Control-Allow-Origin: *
diff --git a/tests/wpt/web-platform-tests/origin-isolation/resources/send-origin-isolation-header.py b/tests/wpt/web-platform-tests/origin-isolation/resources/send-origin-isolation-header.py
index 67d85620af1..02976a9c056 100644
--- a/tests/wpt/web-platform-tests/origin-isolation/resources/send-origin-isolation-header.py
+++ b/tests/wpt/web-platform-tests/origin-isolation/resources/send-origin-isolation-header.py
@@ -5,13 +5,13 @@ def main(request, response):
     to the parent. See ./helpers.mjs for how these handlers are used.
     """
 
-    if "header" in request.GET:
-      header = request.GET.first("header")
-      response.headers.set("Origin-Isolation", header)
+    if b"header" in request.GET:
+      header = request.GET.first(b"header")
+      response.headers.set(b"Origin-Isolation", header)
 
-    response.headers.set("Content-Type", "text/html")
+    response.headers.set(b"Content-Type", b"text/html")
 
-    return """
+    return u"""
     <!DOCTYPE html>
     <meta charset="utf-8">
     <title>Helper page for origin isolation tests</title>
diff --git a/tests/wpt/web-platform-tests/origin-policy/bad-server/resources/subframe-with-bad-header.py b/tests/wpt/web-platform-tests/origin-policy/bad-server/resources/subframe-with-bad-header.py
index c35daa0c2be..3fc6c1c942b 100644
--- a/tests/wpt/web-platform-tests/origin-policy/bad-server/resources/subframe-with-bad-header.py
+++ b/tests/wpt/web-platform-tests/origin-policy/bad-server/resources/subframe-with-bad-header.py
@@ -1,12 +1,12 @@
 def main(request, response):
     """Send a response with the Origin-Policy header given in the query string.
     """
-    header = request.GET.first("header")
+    header = request.GET.first(b"header")
 
-    response.headers.set("Origin-Policy", header)
-    response.headers.set("Content-Type", "text/html")
+    response.headers.set(b"Origin-Policy", header)
+    response.headers.set(b"Content-Type", b"text/html")
 
-    return """
+    return u"""
     <!DOCTYPE html>
     <meta charset="utf-8">
     <title>Origin policy bad header subframe</title>
diff --git a/tests/wpt/web-platform-tests/origin-policy/resources/subframe-with-origin-policy.py b/tests/wpt/web-platform-tests/origin-policy/resources/subframe-with-origin-policy.py
index 68e3e207185..27389e83bfa 100644
--- a/tests/wpt/web-platform-tests/origin-policy/resources/subframe-with-origin-policy.py
+++ b/tests/wpt/web-platform-tests/origin-policy/resources/subframe-with-origin-policy.py
@@ -7,14 +7,14 @@ def main(request, response):
        since it will otherwise be interpreted relative to where this file is
        served.
     """
-    test_file = request.GET.first("test")
+    test_file = request.GET.first(b"test")
 
-    expected_ids = request.GET.first("expectedIds")
+    expected_ids = request.GET.first(b"expectedIds")
 
-    response.headers.set("Origin-Policy", "allowed=(latest)")
-    response.headers.set("Content-Type", "text/html")
+    response.headers.set(b"Origin-Policy", b"allowed=(latest)")
+    response.headers.set(b"Content-Type", b"text/html")
 
-    ret_val = """
+    ret_val = b"""
     <!DOCTYPE html>
     <meta charset="utf-8">
     <title>Origin policy subframe</title>
@@ -26,8 +26,8 @@ def main(request, response):
     <script type="module" src="%s"></script>
   """ % test_file
 
-    if expected_ids != "undefined":
-      ret_val += """
+    if expected_ids != b"undefined":
+      ret_val += b"""
       <script type="module">
         test(() => {
           assert_array_equals(originPolicyIds, %s);
diff --git a/tests/wpt/web-platform-tests/presentation-api/controlling-ua/support/stash.py b/tests/wpt/web-platform-tests/presentation-api/controlling-ua/support/stash.py
index 5bddc7160f2..83653d365a7 100644
--- a/tests/wpt/web-platform-tests/presentation-api/controlling-ua/support/stash.py
+++ b/tests/wpt/web-platform-tests/presentation-api/controlling-ua/support/stash.py
@@ -1,9 +1,9 @@
 def main(request, response):
-    key = request.GET.first("id")
+    key = request.GET.first(b"id")
 
-    if request.method == "POST":
+    if request.method == u"POST":
         request.server.stash.put(key, request.body)
-        return "ok"
+        return b"ok"
     else:
         value = request.server.stash.take(key)
         assert request.server.stash.take(key) is None
diff --git a/tests/wpt/web-platform-tests/presentation-api/receiving-ua/support/stash.py b/tests/wpt/web-platform-tests/presentation-api/receiving-ua/support/stash.py
index 5bddc7160f2..83653d365a7 100644
--- a/tests/wpt/web-platform-tests/presentation-api/receiving-ua/support/stash.py
+++ b/tests/wpt/web-platform-tests/presentation-api/receiving-ua/support/stash.py
@@ -1,9 +1,9 @@
 def main(request, response):
-    key = request.GET.first("id")
+    key = request.GET.first(b"id")
 
-    if request.method == "POST":
+    if request.method == u"POST":
         request.server.stash.put(key, request.body)
-        return "ok"
+        return b"ok"
     else:
         value = request.server.stash.take(key)
         assert request.server.stash.take(key) is None
diff --git a/tests/wpt/web-platform-tests/referrer-policy/generic/resources/referrer.py b/tests/wpt/web-platform-tests/referrer-policy/generic/resources/referrer.py
index a969b80f54b..2d15dc09c4e 100644
--- a/tests/wpt/web-platform-tests/referrer-policy/generic/resources/referrer.py
+++ b/tests/wpt/web-platform-tests/referrer-policy/generic/resources/referrer.py
@@ -1,10 +1,10 @@
 def main(request, response):
     response_headers = [(b"Access-Control-Allow-Origin", b"*")]
-    body = """
+    body = b"""
     <p id=referrer>%s</p>
     <script>
       const referrer_text = referrer.textContent;
       window.parent.postMessage(referrer_text, "*");
     </script>
-    """ % request.headers.get("referer", "")
+    """ % request.headers.get(b"referer", b"")
     return (200, response_headers, body)
diff --git a/tests/wpt/web-platform-tests/reporting/resources/report.py b/tests/wpt/web-platform-tests/reporting/resources/report.py
index d31b47429ec..a3a0ee5ddba 100644
--- a/tests/wpt/web-platform-tests/reporting/resources/report.py
+++ b/tests/wpt/web-platform-tests/reporting/resources/report.py
@@ -1,17 +1,17 @@
 import json
 
 def main(request, response):
-  key = request.GET.first('id')
+  key = request.GET.first(b'id')
 
   # No CORS support for cross-origin reporting endpoints
-  if request.method == 'POST':
+  if request.method == u'POST':
     reports = request.server.stash.take(key) or []
     for report in json.loads(request.body):
       reports.append(report)
     request.server.stash.put(key, reports)
-    return 'done'
-  if request.method == 'GET':
+    return b'done'
+  if request.method == u'GET':
     return json.dumps(request.server.stash.take(key) or [])
 
   response.status = 400
-  return 'invalid method'
\ No newline at end of file
+  return b'invalid method'
diff --git a/tests/wpt/web-platform-tests/service-workers/cache-storage/resources/fetch-status.py b/tests/wpt/web-platform-tests/service-workers/cache-storage/resources/fetch-status.py
index 71f13ebc3a5..b7109f4787f 100644
--- a/tests/wpt/web-platform-tests/service-workers/cache-storage/resources/fetch-status.py
+++ b/tests/wpt/web-platform-tests/service-workers/cache-storage/resources/fetch-status.py
@@ -1,2 +1,2 @@
 def main(request, response):
-    return int(request.GET["status"]), [], ""
+    return int(request.GET[b"status"]), [], b""
diff --git a/tests/wpt/web-platform-tests/service-workers/cache-storage/resources/vary.py b/tests/wpt/web-platform-tests/service-workers/cache-storage/resources/vary.py
index a609d7e8758..e7a914eca82 100644
--- a/tests/wpt/web-platform-tests/service-workers/cache-storage/resources/vary.py
+++ b/tests/wpt/web-platform-tests/service-workers/cache-storage/resources/vary.py
@@ -1,27 +1,27 @@
 from six import text_type
 
 def main(request, response):
-  if "clear-vary-value-override-cookie" in request.GET:
-    response.unset_cookie("vary-value-override")
-    return "vary cookie cleared"
+  if b"clear-vary-value-override-cookie" in request.GET:
+    response.unset_cookie(b"vary-value-override")
+    return b"vary cookie cleared"
 
-  set_cookie_vary = request.GET.first("set-vary-value-override-cookie",
-                                      default="")
+  set_cookie_vary = request.GET.first(b"set-vary-value-override-cookie",
+                                      default=b"")
   if set_cookie_vary:
-    response.set_cookie("vary-value-override", set_cookie_vary)
-    return "vary cookie set"
+    response.set_cookie(b"vary-value-override", set_cookie_vary)
+    return b"vary cookie set"
 
   # If there is a vary-value-override cookie set, then use its value
   # for the VARY header no matter what the query string is set to.  This
   # override is necessary to test the case when two URLs are identical
   # (including query), but differ by VARY header.
-  cookie_vary = request.cookies.get("vary-value-override");
+  cookie_vary = request.cookies.get(b"vary-value-override");
   if cookie_vary:
-    response.headers.set("vary", text_type(cookie_vary))
+    response.headers.set(b"vary", text_type(cookie_vary))
   else:
     # If there is no cookie, then use the query string value, if present.
-    query_vary = request.GET.first("vary", default="")
+    query_vary = request.GET.first(b"vary", default=b"")
     if query_vary:
-      response.headers.set("vary", query_vary)
+      response.headers.set(b"vary", query_vary)
 
-  return "vary response"
+  return b"vary response"
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/ServiceWorkerGlobalScope/resources/update-worker.py b/tests/wpt/web-platform-tests/service-workers/service-worker/ServiceWorkerGlobalScope/resources/update-worker.py
index 5158bf25170..8a87e1baa4c 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/ServiceWorkerGlobalScope/resources/update-worker.py
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/ServiceWorkerGlobalScope/resources/update-worker.py
@@ -1,14 +1,16 @@
 import os
 import time
 
+from wptserve.utils import isomorphic_decode
+
 def main(request, response):
     # update() does not bypass cache so set the max-age to 0 such that update()
     # can find a new version in the network.
-    headers = [('Cache-Control', 'max-age: 0'),
-               ('Content-Type', 'application/javascript')]
-    with open(os.path.join(os.path.dirname(__file__),
-                           'update-worker.js'), 'r') as file:
+    headers = [(b'Cache-Control', b'max-age: 0'),
+               (b'Content-Type', b'application/javascript')]
+    with open(os.path.join(os.path.dirname(isomorphic_decode(__file__)),
+                           u'update-worker.js'), u'r') as file:
         script = file.read()
     # Return a different script for each access.
-    return headers, '// %s\n%s' % (time.time(), script)
+    return headers, u'// %s\n%s' % (time.time(), script)
 
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/chunked-encoding-scope.py b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/chunked-encoding-scope.py
index 3521b64f50f..912f43d0040 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/chunked-encoding-scope.py
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/chunked-encoding-scope.py
@@ -1,20 +1,20 @@
 import time
 
 def main(request, response):
-    use_broken_body = 'use_broken_body' in request.GET
+    use_broken_body = b'use_broken_body' in request.GET
 
     response.add_required_headers = False
     response.writer.write_status(200)
-    response.writer.write_header("Content-type", "text/html; charset=UTF-8")
-    response.writer.write_header("Transfer-encoding", "chunked")
+    response.writer.write_header(b"Content-type", b"text/html; charset=UTF-8")
+    response.writer.write_header(b"Transfer-encoding", b"chunked")
     response.writer.end_headers()
 
     for idx in range(10):
         if use_broken_body:
-            response.writer.write("%s\n%s\n" % (len(str(idx)), idx))
+            response.writer.write(u"%s\n%s\n" % (len(str(idx)), idx))
         else:
-            response.writer.write("%s\r\n%s\r\n" % (len(str(idx)), idx))
+            response.writer.write(u"%s\r\n%s\r\n" % (len(str(idx)), idx))
         response.writer.flush()
         time.sleep(0.001)
 
-    response.writer.write("0\r\n\r\n")
+    response.writer.write(u"0\r\n\r\n")
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/cookie.py b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/cookie.py
index 60688d94382..30a1dd498a5 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/cookie.py
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/cookie.py
@@ -4,17 +4,17 @@ def main(request, response):
     The body will be "1" if the cookie is present in the request and `drop` parameter is "0",
     otherwise the body will be "0".
     """
-    same_site = request.GET.first("same-site")
-    cookie_name = request.GET.first("cookie-name")
-    drop = request.GET.first("drop")
-    cookie_in_request = "0"
-    cookie = "%s=1; Secure; SameSite=%s" % (cookie_name, same_site)
+    same_site = request.GET.first(b"same-site")
+    cookie_name = request.GET.first(b"cookie-name")
+    drop = request.GET.first(b"drop")
+    cookie_in_request = b"0"
+    cookie = b"%s=1; Secure; SameSite=%s" % (cookie_name, same_site)
 
-    if drop == "1":
-        cookie += "; Max-Age=0"
+    if drop == b"1":
+        cookie += b"; Max-Age=0"
 
     if request.cookies.get(cookie_name):
         cookie_in_request = request.cookies[cookie_name].value
 
-    headers = [('Content-Type', 'text/html'), ('Set-Cookie', cookie)]
+    headers = [(b'Content-Type', b'text/html'), (b'Set-Cookie', cookie)]
     return (200, headers, cookie_in_request)
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/redirect-scope.py b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/redirect-scope.py
index 07ddd097690..2e7ae0163cb 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/redirect-scope.py
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/redirect-scope.py
@@ -1,37 +1,37 @@
 def main(request, response):
-    if "base" in request.GET:
-        return [("Content-Type", "text/html")], "OK"
-    type = request.GET.first("type")
+    if b"base" in request.GET:
+        return [(b"Content-Type", b"text/html")], b"OK"
+    type = request.GET.first(b"type")
 
-    if type == "normal":
+    if type == b"normal":
         response.status = 302
-        response.headers.append("Location", "redirect-redirected.html")
-        response.headers.append("Custom-Header", "hello")
-        return ""
+        response.headers.append(b"Location", b"redirect-redirected.html")
+        response.headers.append(b"Custom-Header", b"hello")
+        return b""
 
-    if type == "no-location":
+    if type == b"no-location":
         response.status = 302
-        response.headers.append("Custom-Header", "hello")
-        return ""
+        response.headers.append(b"Custom-Header", b"hello")
+        return b""
 
-    if type == "no-location-with-body":
+    if type == b"no-location-with-body":
         response.status = 302
-        response.headers.append("Content-Type", "text/html")
-        response.headers.append("Custom-Header", "hello")
-        return "<body>BODY</body>"
+        response.headers.append(b"Content-Type", b"text/html")
+        response.headers.append(b"Custom-Header", b"hello")
+        return b"<body>BODY</body>"
 
-    if type == "redirect-to-scope":
+    if type == b"redirect-to-scope":
         response.status = 302
-        response.headers.append("Location",
-                                "redirect-scope.py?type=redirect-to-scope2")
-        return ""
-    if type == "redirect-to-scope2":
+        response.headers.append(b"Location",
+                                b"redirect-scope.py?type=redirect-to-scope2")
+        return b""
+    if type == b"redirect-to-scope2":
         response.status = 302
-        response.headers.append("Location",
-                                "redirect-scope.py?type=redirect-to-scope3")
-        return ""
-    if type == "redirect-to-scope3":
+        response.headers.append(b"Location",
+                                b"redirect-scope.py?type=redirect-to-scope3")
+        return b""
+    if type == b"redirect-to-scope3":
         response.status = 302
-        response.headers.append("Location", "redirect-redirected.html")
-        response.headers.append("Custom-Header", "hello")
-        return ""
+        response.headers.append(b"Location", b"redirect-redirected.html")
+        response.headers.append(b"Custom-Header", b"hello")
+        return b""
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/request-headers-scope.py b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/request-headers-scope.py
index 04320b72c20..46151cdcbb0 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/request-headers-scope.py
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/request-headers-scope.py
@@ -1,9 +1,12 @@
 import json
 
+from wptserve.utils import isomorphic_decode
+
 def main(request, response):
     normalized = dict()
 
-    for key, values in dict(request.headers).iteritems():
-        normalized[key.upper()] = values
+    for key, values in dict(request.headers).items():
+        values = [isomorphic_decode(value) for value in values]
+        normalized[isomorphic_decode(key.upper())] = values
 
     return json.dumps(normalized)
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/resource-timing-scope.py b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/resource-timing-scope.py
index 1820be4400e..856f9dbc2a4 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/resource-timing-scope.py
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/navigation-preload/resources/resource-timing-scope.py
@@ -1,19 +1,19 @@
 import zlib
 
 def main(request, response):
-    type = request.GET.first("type")
+    type = request.GET.first(b"type")
 
     if type == "normal":
-        content = "This is Navigation Preload Resource Timing test."
+        content = b"This is Navigation Preload Resource Timing test."
         output = zlib.compress(content, 9)
-        headers = [("Content-type", "text/plain"),
-                   ("Content-Encoding", "deflate"),
-                   ("X-Decoded-Body-Size", len(content)),
-                   ("X-Encoded-Body-Size", len(output)),
-                   ("Content-Length", len(output))]
+        headers = [(b"Content-type", b"text/plain"),
+                   (b"Content-Encoding", b"deflate"),
+                   (b"X-Decoded-Body-Size", len(content)),
+                   (b"X-Encoded-Body-Size", len(output)),
+                   (b"Content-Length", len(output))]
         return headers, output
 
-    if type == "redirect":
+    if type == b"redirect":
         response.status = 302
-        response.headers.append("Location", "redirect-redirected.html")
-        return ""
+        response.headers.append(b"Location", b"redirect-redirected.html")
+        return b""
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/resources/404.py b/tests/wpt/web-platform-tests/service-workers/service-worker/resources/404.py
index 235a3d4ff0e..1ee4af169e7 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/resources/404.py
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/resources/404.py
@@ -2,4 +2,4 @@
 # text/plain or text/html so this script exists if you want to test a 404 load
 # in an iframe.
 def main(req, res):
-    return 404, [('Content-Type', 'text/plain')], "Page not found"
+    return 404, [(b'Content-Type', b'text/plain')], b"Page not found"
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/resources/about-blank-replacement-frame.py b/tests/wpt/web-platform-tests/service-workers/service-worker/resources/about-blank-replacement-frame.py
index 643142dbea1..a29ff9d4134 100644
--- a/tests/wpt/web-platform-tests/service-workers/service-worker/resources/about-blank-replacement-frame.py
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/resources/about-blank-replacement-frame.py
@@ -1,11 +1,11 @@
 def main(request, response):
-  if 'nested' in request.GET:
+  if b'nested' in request.GET:
     return (
-      [('Content-Type', 'text/html')],
-      'failed: nested frame was not intercepted by the service worker'
+      [(b'Content-Type', b'text/html')],
+      b'failed: nested frame was not intercepted by the service worker'
     )
 
-  return ([('Content-Type', 'text/html')], """
+  return ([(b'Content-Type', b'text/html')], b"""
 <!doctype html>
 <html>
 <body>
diff --git a/tests/wpt/web-platform-tests/tools/requirements_mypy.txt b/tests/wpt/web-platform-tests/tools/requirements_mypy.txt
index dc5df8ef9ec..fae3597764c 100644
--- a/tests/wpt/web-platform-tests/tools/requirements_mypy.txt
+++ b/tests/wpt/web-platform-tests/tools/requirements_mypy.txt
@@ -1,3 +1,3 @@
-mypy==0.781
+mypy==0.782
 mypy-extensions==0.4.3
 typed-ast==1.4.1
diff --git a/tests/wpt/web-platform-tests/upgrade-insecure-requests/support/redirect-cors.py b/tests/wpt/web-platform-tests/upgrade-insecure-requests/support/redirect-cors.py
index 56493e0056f..58b19a2ce2d 100644
--- a/tests/wpt/web-platform-tests/upgrade-insecure-requests/support/redirect-cors.py
+++ b/tests/wpt/web-platform-tests/upgrade-insecure-requests/support/redirect-cors.py
@@ -1,5 +1,5 @@
 def main(request, response):
     response.status = 302
-    location = request.GET.first("location")
-    response.headers.set("Location", location)
-    response.headers.set("Access-Control-Allow-Origin", "*")
+    location = request.GET.first(b"location")
+    response.headers.set(b"Location", location)
+    response.headers.set(b"Access-Control-Allow-Origin", b"*")
diff --git a/tests/wpt/web-platform-tests/wasm/webapi/status.py b/tests/wpt/web-platform-tests/wasm/webapi/status.py
index 60c5320df00..9f056678c12 100644
--- a/tests/wpt/web-platform-tests/wasm/webapi/status.py
+++ b/tests/wpt/web-platform-tests/wasm/webapi/status.py
@@ -1,4 +1,4 @@
 def main(request, response):
-    status = int(request.GET["status"])
+    status = int(request.GET[b"status"])
     module = b"\0asm\1\0\0\0"
-    return status, [("Content-Type", "application/wasm")], module
+    return status, [(b"Content-Type", b"application/wasm")], module
diff --git a/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-process-zero-outputs.https.html b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-process-zero-outputs.https.html
new file mode 100644
index 00000000000..e1c19f0d759
--- /dev/null
+++ b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-process-zero-outputs.https.html
@@ -0,0 +1,36 @@
+<!doctype html>
+<html>
+  <head>
+    <title>
+      Test if |outputs| argument is all zero in AudioWorkletProcessor.process()
+    </title>
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+    <script src="/webaudio/resources/audit.js"></script>
+  </head>
+
+  <body>
+    <script>
+      const audit = Audit.createTaskRunner();
+      const filePath = 'processors/zero-outputs-check-processor.js';
+      const context = new AudioContext();
+
+      // Test if the incoming arrays are frozen as expected.
+      audit.define('check-zero-outputs', (task, should) => {
+        context.audioWorklet.addModule(filePath).then(() => {
+          const workletNode =
+              new AudioWorkletNode(context, 'zero-outputs-check-processor');
+          workletNode.port.onmessage = (message) => {
+            const actual = message.data;
+            if (actual.type === 'assertion') {
+              should(actual.success, actual.message).beTrue();
+              task.done();
+            }
+          };
+        });
+      });
+
+      audit.run();
+    </script>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/processors/zero-outputs-check-processor.js b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/processors/zero-outputs-check-processor.js
new file mode 100644
index 00000000000..f816e918a29
--- /dev/null
+++ b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-audioworklet-interface/processors/zero-outputs-check-processor.js
@@ -0,0 +1,78 @@
+/**
+ * Returns true if a given AudioPort is completely filled with zero samples.
+ * "AudioPort" is a short-hand for FrozenArray<FrozenArray<Float32Array>>.
+ *
+ * @param {FrozenArray<FrozenArray<Float32Array>>} audioPort
+ * @returns bool
+ */
+function IsAllZero(audioPort) {
+  for (let busIndex = 0; busIndex < audioPort.length; ++busIndex) {
+    const audioBus = audioPort[busIndex];
+    for (let channelIndex = 0; channelIndex < audioBus.length; ++channelIndex) {
+      const audioChannel = audioBus[channelIndex];
+      for (let sample = 0; sample < audioChannel.length; ++sample) {
+        if (audioChannel[sample] != 0)
+          return false;
+      }
+    }
+  }
+  return true;
+}
+
+const kRenderQuantumFrames = 128;
+const kTestLengthInSec = 1.0;
+const kPulseDuration = 100;
+
+/**
+ * Checks the |outputs| argument of AudioWorkletProcessor.process() and
+ * send a message to an associated AudioWorkletNode. It needs to be all zero
+ * at all times.
+ *
+ * @class ZeroOutputsCheckProcessor
+ * @extends {AudioWorkletProcessor}
+ */
+class ZeroOutputsCheckProcessor extends AudioWorkletProcessor {
+  constructor() {
+    super();
+    this.startTime = currentTime;
+    this.counter = 0;
+  }
+
+  process(inputs, outputs) {
+    if (!IsAllZero(outputs)) {
+      this.port.postMessage({
+        type: 'assertion',
+        success: false,
+        message: 'Unexpected Non-zero sample found in |outputs|.'
+      });
+      return false;
+    }
+
+    if (currentTime - this.startTime >= kTestLengthInSec) {
+      this.port.postMessage({
+        type: 'assertion',
+        success: true,
+        message: `|outputs| has been all zeros for ${kTestLengthInSec} ` +
+            'seconds as expected.'
+      });
+      return false;
+    }
+
+    // Every ~0.25 second (100 render quanta), switch between outputting white
+    // noise and just exiting without doing anything. (from crbug.com/1099756)
+    this.counter++;
+    if (Math.floor(this.counter / kPulseDuration) % 2 == 0)
+      return true;
+
+    let output = outputs[0];
+    for (let channel = 0; channel < output.length; ++channel) {
+      for (let sample = 0; sample < 128; sample++) {
+        output[channel][sample] = 0.1 * (Math.random() - 0.5);
+      }
+    }
+
+    return true;
+  }
+}
+
+registerProcessor('zero-outputs-check-processor', ZeroOutputsCheckProcessor);
diff --git a/tests/wpt/web-platform-tests/xhr/resources/status.py b/tests/wpt/web-platform-tests/xhr/resources/status.py
index 5d72e10b24b..05a59d5a637 100644
--- a/tests/wpt/web-platform-tests/xhr/resources/status.py
+++ b/tests/wpt/web-platform-tests/xhr/resources/status.py
@@ -1,9 +1,11 @@
+from wptserve.utils import isomorphic_encode
+
 def main(request, response):
-    code = int(request.GET.first("code", 200))
-    text = request.GET.first("text", "OMG")
-    content = request.GET.first("content", "")
-    type = request.GET.first("type", "")
+    code = int(request.GET.first(b"code", 200))
+    text = request.GET.first(b"text", b"OMG")
+    content = request.GET.first(b"content", b"")
+    type = request.GET.first(b"type", b"")
     status = (code, text)
-    headers = [("Content-Type", type),
-               ("X-Request-Method", request.method)]
+    headers = [(b"Content-Type", type),
+               (b"X-Request-Method", isomorphic_encode(request.method))]
     return status, headers, content
diff --git a/tests/wpt/web-platform-tests/xhr/resources/trickle.py b/tests/wpt/web-platform-tests/xhr/resources/trickle.py
index 418e2459921..4a6bbd7f4f2 100644
--- a/tests/wpt/web-platform-tests/xhr/resources/trickle.py
+++ b/tests/wpt/web-platform-tests/xhr/resources/trickle.py
@@ -1,15 +1,17 @@
 import time
 
+from six.moves import range
+
 def main(request, response):
-    chunk = "TEST_TRICKLE\n"
-    delay = float(request.GET.first("ms", 500)) / 1E3
-    count = int(request.GET.first("count", 50))
-    if "specifylength" in request.GET:
-        response.headers.set("Content-Length", count * len(chunk))
+    chunk = b"TEST_TRICKLE\n"
+    delay = float(request.GET.first(b"ms", 500)) / 1E3
+    count = int(request.GET.first(b"count", 50))
+    if b"specifylength" in request.GET:
+        response.headers.set(b"Content-Length", count * len(chunk))
     time.sleep(delay)
-    response.headers.set("Content-type", "text/plain")
+    response.headers.set(b"Content-type", b"text/plain")
     response.write_status_headers()
     time.sleep(delay)
-    for i in xrange(count):
+    for i in range(count):
         response.writer.write_content(chunk)
         time.sleep(delay)
diff --git a/tests/wpt/web-platform-tests/xhr/resources/upload.py b/tests/wpt/web-platform-tests/xhr/resources/upload.py
index 304bea9e5ef..e35e46edcf9 100644
--- a/tests/wpt/web-platform-tests/xhr/resources/upload.py
+++ b/tests/wpt/web-platform-tests/xhr/resources/upload.py
@@ -1,15 +1,17 @@
+from wptserve.utils import isomorphic_encode
+
 def main(request, response):
     content = []
 
-    for key, values in sorted(item for item in request.POST.items() if not hasattr(item[1][0], "filename")):
-        content.append("%s=%s," % (key, values[0]))
-    content.append("\n")
+    for key, values in sorted(item for item in request.POST.items() if not hasattr(item[1][0], u"filename")):
+        content.append(b"%s=%s," % (key, values[0]))
+    content.append(b"\n")
 
-    for key, values in sorted(item for item in request.POST.items() if hasattr(item[1][0], "filename")):
+    for key, values in sorted(item for item in request.POST.items() if hasattr(item[1][0], u"filename")):
         value = values[0]
-        content.append("%s=%s:%s:%s," % (key,
-                                         value.filename,
-                                         value.headers["Content-Type"],
-                                         len(value.file.read())))
+        content.append(b"%s=%s:%s:%d," % (key,
+                                          isomorphic_encode(value.filename),
+                                          isomorphic_encode(value.headers[u"Content-Type"]) if value.headers[u"Content-Type"] is not None else b"None",
+                                          len(value.file.read())))
 
-    return "".join(content)
+    return b"".join(content)
diff --git a/tests/wpt/web-platform-tests/xhr/resources/win-1252-html.py b/tests/wpt/web-platform-tests/xhr/resources/win-1252-html.py
index a4d72d5e275..0ef5283f7d5 100644
--- a/tests/wpt/web-platform-tests/xhr/resources/win-1252-html.py
+++ b/tests/wpt/web-platform-tests/xhr/resources/win-1252-html.py
@@ -1,5 +1,5 @@
 def main(request, response):
-    headers = [("Content-type", "text/html;charset=windows-1252")]
+    headers = [(b"Content-type", b"text/html;charset=windows-1252")]
     content = chr(0xff)
 
     return headers, content
diff --git a/tests/wpt/web-platform-tests/xhr/resources/win-1252-xml.py b/tests/wpt/web-platform-tests/xhr/resources/win-1252-xml.py
index 09c32e4574b..d88086e936e 100644
--- a/tests/wpt/web-platform-tests/xhr/resources/win-1252-xml.py
+++ b/tests/wpt/web-platform-tests/xhr/resources/win-1252-xml.py
@@ -1,5 +1,5 @@
 def main(request, response):
-    headers = [("Content-type", "application/xml;charset=windows-1252")]
+    headers = [(b"Content-type", b"application/xml;charset=windows-1252")]
     content = '<' + chr(0xff) + '/>'
 
     return headers, content
diff --git a/tests/wpt/web-platform-tests/xhr/resources/zlib.py b/tests/wpt/web-platform-tests/xhr/resources/zlib.py
index 49ed69de793..638813999ce 100644
--- a/tests/wpt/web-platform-tests/xhr/resources/zlib.py
+++ b/tests/wpt/web-platform-tests/xhr/resources/zlib.py
@@ -1,19 +1,19 @@
 import zlib
 
 def main(request, response):
-    if "content" in request.GET:
-        output = request.GET["content"]
+    if b"content" in request.GET:
+        output = request.GET[b"content"]
     else:
         output = request.body
 
     output = zlib.compress(output, 9)
 
-    headers = [("Content-type", "text/plain"),
-               ("Content-Encoding", "deflate"),
-               ("X-Request-Method", request.method),
-               ("X-Request-Query", request.url_parts.query if request.url_parts.query else "NO"),
-               ("X-Request-Content-Length", request.headers.get("Content-Length", "NO")),
-               ("X-Request-Content-Type", request.headers.get("Content-Type", "NO")),
-               ("Content-Length", len(output))]
+    headers = [(b"Content-type", b"text/plain"),
+               (b"Content-Encoding", b"deflate"),
+               (b"X-Request-Method", request.method),
+               (b"X-Request-Query", request.url_parts.query if request.url_parts.query else b"NO"),
+               (b"X-Request-Content-Length", request.headers.get(b"Content-Length", b"NO")),
+               (b"X-Request-Content-Type", request.headers.get(b"Content-Type", b"NO")),
+               (b"Content-Length", len(output))]
 
     return headers, output