diff --git a/tests/wpt/metadata/2dcontext/imagebitmap/createImageBitmap-drawImage.html.ini b/tests/wpt/metadata/2dcontext/imagebitmap/createImageBitmap-drawImage.html.ini
index 8db1ab505b6..57022685d3e 100644
--- a/tests/wpt/metadata/2dcontext/imagebitmap/createImageBitmap-drawImage.html.ini
+++ b/tests/wpt/metadata/2dcontext/imagebitmap/createImageBitmap-drawImage.html.ini
@@ -1,16 +1,17 @@
 [createImageBitmap-drawImage.html]
   type: testharness
+  expected: TIMEOUT
   [createImageBitmap from a HTMLImageElement, and drawImage on the created ImageBitmap]
     expected: FAIL
 
   [createImageBitmap from a Blob, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from a HTMLCanvasElement, and drawImage on the created ImageBitmap]
     expected: FAIL
 
   [createImageBitmap from an ImageBitmap, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from an ImageData, and drawImage on the created ImageBitmap]
     expected: FAIL
@@ -43,13 +44,13 @@
     expected: FAIL
 
   [createImageBitmap from an ImageData with negative sw/sh, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from an ImageBitmap with negative sw/sh, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from a Blob with negative sw/sh, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from a bitmap HTMLImageElement, and drawImage on the created ImageBitmap]
     expected: FAIL
@@ -157,26 +158,26 @@
     expected: FAIL
 
   [createImageBitmap from an ImageData scaled up, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: TIMEOUT
 
   [createImageBitmap from an ImageData resized, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from an ImageBitmap scaled down, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from an ImageBitmap scaled up, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from an ImageBitmap resized, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from a Blob scaled down, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from a Blob scaled up, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
   [createImageBitmap from a Blob resized, and drawImage on the created ImageBitmap]
-    expected: FAIL
+    expected: NOTRUN
 
diff --git a/tests/wpt/metadata/MANIFEST.json b/tests/wpt/metadata/MANIFEST.json
index 78f0fb33d5b..98e9c5d6392 100644
--- a/tests/wpt/metadata/MANIFEST.json
+++ b/tests/wpt/metadata/MANIFEST.json
@@ -264933,16 +264933,6 @@
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-32x32.png": [
-    [
-     {}
-    ]
-   ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-37x37.png": [
-    [
-     {}
-    ]
-   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/background/background-attachment-fixed-inside-transform-1-ref.html": [
     [
      {}
@@ -265068,62 +265058,72 @@
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/border.png": [
-    [
-     {}
-    ]
-   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/background/reftest.list": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-bl.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/aqua-yellow-32x32.png": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-bo.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/aqua-yellow-37x37.png": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-br.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/border.png": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-ct.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-bl.png": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-le.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-bo.png": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-ri.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-br.png": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-tl.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-ct.png": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-to.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-le.png": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-tr.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-ri.png": [
     [
      {}
     ]
    ],
-   "css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule.png": [
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-tl.png": [
+    [
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-to.png": [
+    [
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-tr.png": [
+    [
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule.png": [
     [
      {}
     ]
@@ -281923,6 +281923,11 @@
      {}
     ]
    ],
+   "html/semantics/embedded-content/the-iframe-element/support/iframe-that-opens-modals.html": [
+    [
+     {}
+    ]
+   ],
    "html/semantics/embedded-content/the-iframe-element/support/iframe-that-performs-top-navigation-on-popup.html": [
     [
      {}
@@ -282068,6 +282073,11 @@
      {}
     ]
    ],
+   "html/semantics/embedded-content/the-iframe-element/support/iframe_sandbox_block_modals.js": [
+    [
+     {}
+    ]
+   ],
    "html/semantics/embedded-content/the-iframe-element/support/navigation-changed-iframe.html": [
     [
      {}
@@ -313691,6 +313701,54 @@
      {}
     ]
    ],
+   "css/css-properties-values-api/register-property-syntax-parsing.html": [
+    [
+     "/css/css-properties-values-api/register-property-syntax-parsing.html",
+     {}
+    ]
+   ],
+   "css/css-properties-values-api/register-property.html": [
+    [
+     "/css/css-properties-values-api/register-property.html",
+     {}
+    ]
+   ],
+   "css/css-properties-values-api/registered-properties-inheritance.html": [
+    [
+     "/css/css-properties-values-api/registered-properties-inheritance.html",
+     {}
+    ]
+   ],
+   "css/css-properties-values-api/registered-property-computation.html": [
+    [
+     "/css/css-properties-values-api/registered-property-computation.html",
+     {}
+    ]
+   ],
+   "css/css-properties-values-api/registered-property-cssom.html": [
+    [
+     "/css/css-properties-values-api/registered-property-cssom.html",
+     {}
+    ]
+   ],
+   "css/css-properties-values-api/registered-property-initial.html": [
+    [
+     "/css/css-properties-values-api/registered-property-initial.html",
+     {}
+    ]
+   ],
+   "css/css-properties-values-api/var-reference-registered-properties-cycles.html": [
+    [
+     "/css/css-properties-values-api/var-reference-registered-properties-cycles.html",
+     {}
+    ]
+   ],
+   "css/css-properties-values-api/var-reference-registered-properties.html": [
+    [
+     "/css/css-properties-values-api/var-reference-registered-properties.html",
+     {}
+    ]
+   ],
    "css/css-pseudo/first-letter-property-whitelist.html": [
     [
      "/css/css-pseudo/first-letter-property-whitelist.html",
@@ -324817,6 +324875,12 @@
      {}
     ]
    ],
+   "fetch/api/response/response-error-from-stream.html": [
+    [
+     "/fetch/api/response/response-error-from-stream.html",
+     {}
+    ]
+   ],
    "fetch/api/response/response-error.html": [
     [
      "/fetch/api/response/response-error.html",
@@ -331683,6 +331747,30 @@
      {}
     ]
    ],
+   "html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-1.html": [
+    [
+     "/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-1.html",
+     {}
+    ]
+   ],
+   "html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html": [
+    [
+     "/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html",
+     {}
+    ]
+   ],
+   "html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html": [
+    [
+     "/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html",
+     {}
+    ]
+   ],
+   "html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html": [
+    [
+     "/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html",
+     {}
+    ]
+   ],
    "html/semantics/embedded-content/the-iframe-element/iframe_sandbox_navigate_ancestor-1.html": [
     [
      "/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_navigate_ancestor-1.html",
@@ -390465,7 +390553,7 @@
    "support"
   ],
   "./.travis.yml": [
-   "7e96c68c023309a8d50f572a9b2bc892b523358b",
+   "db5838d29eefceadbb7f088f7de75d765dbaa58c",
    "support"
   ],
   "./CONTRIBUTING.md": [
@@ -390493,7 +390581,7 @@
    "support"
   ],
   "./lint.whitelist": [
-   "f99ce1b3cf312caac08a8a8bb6a970ba00e28160",
+   "82fc9107178a6f9aef6c978ad51afe2370c92de1",
    "support"
   ],
   "./serve.py": [
@@ -400445,7 +400533,7 @@
    "testharness"
   ],
   "bluetooth/characteristic/getDescriptor/gen-characteristic-is-removed.https.html": [
-   "df68f7bf4028cf7d2f32bb291a008d562eac3cad",
+   "6ba1c71fa5c34f7b0321b5430fa79c75c907fc14",
    "testharness"
   ],
   "bluetooth/characteristic/getDescriptor/gen-descriptor-get-same-object.https.html": [
@@ -400453,15 +400541,15 @@
    "testharness"
   ],
   "bluetooth/characteristic/getDescriptor/gen-service-is-removed.https.html": [
-   "ba4c6477eaa5978599e7c77d3227bc63fe6b5a3f",
+   "80c7782e7c2bba33e43d2661a3ba0d069b49e727",
    "testharness"
   ],
   "bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed-with-uuid.https.html": [
-   "ae775a150cda67893dcace79396468134b5b8a60",
+   "fa068af0ac6d1629622f207b77ae95fe3f50b6cc",
    "testharness"
   ],
   "bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed.https.html": [
-   "64c51958f8d520e9608e695ddf0115f460081f2f",
+   "82084e965ad35f176505631cb0b9007422bf3fd4",
    "testharness"
   ],
   "bluetooth/characteristic/getDescriptors/gen-descriptor-get-same-object.https.html": [
@@ -400469,11 +400557,11 @@
    "testharness"
   ],
   "bluetooth/characteristic/getDescriptors/gen-service-is-removed-with-uuid.https.html": [
-   "67a1b69b198711e8c824529c2afe5513284e449f",
+   "ad2b25c264ae236332715ae92e30452c5b97954c",
    "testharness"
   ],
   "bluetooth/characteristic/getDescriptors/gen-service-is-removed.https.html": [
-   "e0746e2c992231bac0ed213b3f9b17a863db0902",
+   "1132700853cbfd7fbc0772e44a407d72f710ffb5",
    "testharness"
   ],
   "bluetooth/characteristic/notifications/characteristic-is-removed.https.html": [
@@ -400481,7 +400569,7 @@
    "testharness"
   ],
   "bluetooth/characteristic/notifications/service-is-removed.https.html": [
-   "c38cba83787c54f68d57f4403a0ec0242c169035",
+   "f6a5be53c85a190dca81a9b425b63d77bc6c193f",
    "testharness"
   ],
   "bluetooth/characteristic/readValue/add-multiple-event-listeners.https.html": [
@@ -400497,7 +400585,7 @@
    "testharness"
   ],
   "bluetooth/characteristic/readValue/gen-characteristic-is-removed.https.html": [
-   "e775062bd01919af48f2c3e11ea2e90702b29064",
+   "1700dfa9ba6e1aa44d42630ef7ba61d4beeed330",
    "testharness"
   ],
   "bluetooth/characteristic/readValue/read-succeeds.https.html": [
@@ -400509,7 +400597,7 @@
    "testharness"
   ],
   "bluetooth/characteristic/readValue/service-is-removed.https.html": [
-   "1267b87396e49b063db2a7e5fe8611ef4f39845d",
+   "b79a74ccf33bc76e6582ee7c1e2f3c277f99ddfb",
    "testharness"
   ],
   "bluetooth/characteristic/service-same-from-2-characteristics.https.html": [
@@ -400521,7 +400609,7 @@
    "testharness"
   ],
   "bluetooth/characteristic/startNotifications/gen-characteristic-is-removed.https.html": [
-   "471854c3309862acd121c7ef8d115b037ec297dd",
+   "97f5d01743721207c5addfb9625fd3da7c0c61e3",
    "testharness"
   ],
   "bluetooth/characteristic/writeValue/characteristic-is-removed.https.html": [
@@ -400529,11 +400617,11 @@
    "testharness"
   ],
   "bluetooth/characteristic/writeValue/gen-characteristic-is-removed.https.html": [
-   "2bad4acf374516e29cb5a259d29a97160917ec58",
+   "62b4bd66196c9c833631916761b41e973aa2a554",
    "testharness"
   ],
   "bluetooth/characteristic/writeValue/service-is-removed.https.html": [
-   "570bba21ad98a428dd5575dc544962b8ae6a05d8",
+   "857ae985ba4d15bcc5d78671a7f21d990c8db9c5",
    "testharness"
   ],
   "bluetooth/characteristic/writeValue/write-succeeds.https.html": [
@@ -400541,7 +400629,7 @@
    "testharness"
   ],
   "bluetooth/descriptor/readValue/gen-service-is-removed.https.html": [
-   "c1954f13b95b9f5d0dbfd4f696aa0874e2a47c88",
+   "47f1bd316ae7d2637524a1b5d4436a3f11b20fd0",
    "testharness"
   ],
   "bluetooth/descriptor/readValue/read-succeeds.https.html": [
@@ -400549,7 +400637,7 @@
    "testharness"
   ],
   "bluetooth/descriptor/writeValue/gen-service-is-removed.https.html": [
-   "99c77b594dcdfa971bdf96b28c176bf2e44a98ca",
+   "07c2dc0a081786302040942a989cc49f6b3fa3ca",
    "testharness"
   ],
   "bluetooth/device/gattserverdisconnected-event/disconnected.https.html": [
@@ -400753,7 +400841,7 @@
    "support"
   ],
   "bluetooth/script-tests/characteristic/characteristic-is-removed.js": [
-   "a82d6a1761e402906aa89a790166bccf1dd0a2c2",
+   "7b7cd34d4c480e62fcde4667f50212cbae7f7b07",
    "support"
   ],
   "bluetooth/script-tests/characteristic/descriptor-get-same-object.js": [
@@ -400761,11 +400849,11 @@
    "support"
   ],
   "bluetooth/script-tests/characteristic/service-is-removed.js": [
-   "c4703192b632d2bc63609b717d5f7829aad6168e",
+   "a9fa621bca75da2887835c529b40429a20ebdff8",
    "support"
   ],
   "bluetooth/script-tests/descriptor/service-is-removed.js": [
-   "ef6afb686e14a5b77cc88f6c51c18529739fc7ea",
+   "d442ab654680a3f4c7eae6036f74a20f0b730351",
    "support"
   ],
   "bluetooth/script-tests/server/disconnect-called-before.js": [
@@ -400857,7 +400945,7 @@
    "support"
   ],
   "bluetooth/script-tests/service/service-is-removed.js": [
-   "209d46cebac1cf324dacb9741bbd7a320b70651c",
+   "ef77b77f70ac720b536882e9b48d7fe66fe4ecf4",
    "support"
   ],
   "bluetooth/server/connect/connection-succeeds.https.html": [
@@ -401129,7 +401217,7 @@
    "testharness"
   ],
   "bluetooth/service/getCharacteristic/gen-service-is-removed.https.html": [
-   "8680cb14d493830e9e5ded9d4d07a6e12e2f2fee",
+   "9f698f4e02985f21f772d38942d7fe9f383600f0",
    "testharness"
   ],
   "bluetooth/service/getCharacteristics/blocklisted-characteristics.https.html": [
@@ -401185,11 +401273,11 @@
    "testharness"
   ],
   "bluetooth/service/getCharacteristics/gen-service-is-removed-with-uuid.https.html": [
-   "b67765aaf66b9ac679e018014127836ae9a1753e",
+   "d8e4257645340adfd45f069c4cebbc3ca88f2348",
    "testharness"
   ],
   "bluetooth/service/getCharacteristics/gen-service-is-removed.https.html": [
-   "baadfc8451547b9b1a863b222009f230fc2b032b",
+   "417d39a317f55a95180c806d28047c85dd959d65",
    "testharness"
   ],
   "clear-site-data/navigation-insecure.html": [
@@ -504556,6 +504644,38 @@
    "c7b441a3a07276cad9528dd3ef7d82844d06e2d8",
    "support"
   ],
+  "css/css-properties-values-api/register-property-syntax-parsing.html": [
+   "b065f4840b3c1deb4a2f8a59428e102f2ae11686",
+   "testharness"
+  ],
+  "css/css-properties-values-api/register-property.html": [
+   "df61ce5dd13847deaa9b7165dd1277c1ddefb646",
+   "testharness"
+  ],
+  "css/css-properties-values-api/registered-properties-inheritance.html": [
+   "131676bfa0733a64b679473b411ef651a9df1ab0",
+   "testharness"
+  ],
+  "css/css-properties-values-api/registered-property-computation.html": [
+   "875acfd6e6446e4cb14fcd19fe16e83630b5fe31",
+   "testharness"
+  ],
+  "css/css-properties-values-api/registered-property-cssom.html": [
+   "0fecf81c4089cb67107a9339ee52cd2c44cde60b",
+   "testharness"
+  ],
+  "css/css-properties-values-api/registered-property-initial.html": [
+   "fc0b90f23ea8c8dab20baa3fecdd7d60863527b6",
+   "testharness"
+  ],
+  "css/css-properties-values-api/var-reference-registered-properties-cycles.html": [
+   "bc061780caa0085fca5b003c1aed68c7b162eabd",
+   "testharness"
+  ],
+  "css/css-properties-values-api/var-reference-registered-properties.html": [
+   "988badd19fd1880446db9827e3d96cb4961732a0",
+   "testharness"
+  ],
   "css/css-pseudo/OWNERS": [
    "e196548942a4d77448f734235b3456e2a830a5a7",
    "support"
@@ -524221,7 +524341,7 @@
    "reftest"
   ],
   "css/css-values/calc-in-color-001.html": [
-   "32a0face898f08b854ac392c75368282d718be32",
+   "6a88138c89c65b513310fb27e1f301ab1d652c98",
    "testharness"
   ],
   "css/css-values/calc-in-font-feature-settings.html": [
@@ -535956,14 +536076,6 @@
    "0332d163ba2a010b5a8102cf23d220342e007170",
    "support"
   ],
-  "css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-32x32.png": [
-   "a4c3777cf587ade235c71b27144eae3f307deb05",
-   "support"
-  ],
-  "css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-37x37.png": [
-   "fc2d8a4c94a5a7c19344d5fdeb6f2e0c97e0ea56",
-   "support"
-  ],
   "css/vendor-imports/mozilla/mozilla-central-reftests/background/background-attachment-fixed-inside-transform-1-ref.html": [
    "ac4a007e9956b008807349d6fb1a5e1d04fa70b0",
    "support"
@@ -535973,139 +536085,139 @@
    "reftest"
   ],
   "css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1-ref.html": [
-   "29441a01afe2699a04c4d5ba99acd6b62dc5f96b",
+   "527a9e170665067a0be9c80d5a03e5e3762fb5d0",
    "support"
   ],
   "css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1a.html": [
-   "809a3f95a27d65858ffb02e117730bb42736fb80",
+   "2e63657cd77715a2592071cecfe9a8b92ee25036",
    "reftest"
   ],
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+   "support"
+  ],
   "html/semantics/embedded-content/the-iframe-element/support/navigation-changed-iframe.html": [
    "9dd191a0b5d9c15972363e260228956f7f487c7d",
    "support"
@@ -570913,7 +571061,7 @@
    "support"
   ],
   "interfaces/dom.idl": [
-   "605bb139c7695e46f8657097cf2d9bc6240a2d38",
+   "2d65a8029a80cfc97398d18f911f1ae65067e765",
    "support"
   ],
   "interfaces/encrypted-media.idl": [
@@ -589993,7 +590141,7 @@
    "support"
   ],
   "sensors/generic-sensor-tests.js": [
-   "0f1cea2c0d3f38220cbfdbe4f47d713214987cbd",
+   "383a4f839c4a74b5b4d2a6cff9c83a61bc5aee04",
    "support"
   ],
   "sensors/idlharness.https.html": [
diff --git a/tests/wpt/metadata/dom/nodes/Element-classlist.html.ini b/tests/wpt/metadata/dom/nodes/Element-classlist.html.ini
index 95c9293d995..7bfd658f072 100644
--- a/tests/wpt/metadata/dom/nodes/Element-classlist.html.ini
+++ b/tests/wpt/metadata/dom/nodes/Element-classlist.html.ini
@@ -75,3 +75,333 @@
   [classList.replace("c", "a") with attribute value "c b a" (foo node)]
     expected: FAIL
 
+  [classList.replace("a", "b") with attribute value "a" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("A", "b") with attribute value "a" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "A") with attribute value "a b" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("d", "e") with attribute value "a b c" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("c", "d") with attribute value "a a a  b" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value null (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value "" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " " (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " a  \\f" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "d") with attribute value "a b c" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b c" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "a b a" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "a b a" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "   a  a b" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "   a  a b" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (HTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (HTML node)]
+    expected: FAIL
+
+  [classList.replace(null, "b") with attribute value "a null" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", null) with attribute value "a b" (HTML node)]
+    expected: FAIL
+
+  [classList.replace(undefined, "b") with attribute value "a undefined" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", undefined) with attribute value "a b" (HTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value "a" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("A", "b") with attribute value "a" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "A") with attribute value "a b" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("d", "e") with attribute value "a b c" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("c", "d") with attribute value "a a a  b" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value null (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value "" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " " (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " a  \\f" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "d") with attribute value "a b c" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b c" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "a b a" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "a b a" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "   a  a b" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "   a  a b" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (XHTML node)]
+    expected: FAIL
+
+  [classList.replace(null, "b") with attribute value "a null" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", null) with attribute value "a b" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace(undefined, "b") with attribute value "a undefined" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", undefined) with attribute value "a b" (XHTML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value "a" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("A", "b") with attribute value "a" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("b", "A") with attribute value "a b" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("d", "e") with attribute value "a b c" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("c", "d") with attribute value "a a a  b" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value null (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value "" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " " (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " a  \\f" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("b", "d") with attribute value "a b c" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b c" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "a b a" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "a b a" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "   a  a b" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "   a  a b" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (MathML node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (MathML node)]
+    expected: FAIL
+
+  [classList.replace(null, "b") with attribute value "a null" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", null) with attribute value "a b" (MathML node)]
+    expected: FAIL
+
+  [classList.replace(undefined, "b") with attribute value "a undefined" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", undefined) with attribute value "a b" (MathML node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value "a" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("A", "b") with attribute value "a" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("b", "A") with attribute value "a b" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("d", "e") with attribute value "a b c" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("c", "d") with attribute value "a a a  b" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value null (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value "" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " " (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " a  \\f" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("b", "d") with attribute value "a b c" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b c" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "a b a" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "a b a" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "   a  a b" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "   a  a b" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace(null, "b") with attribute value "a null" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", null) with attribute value "a b" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace(undefined, "b") with attribute value "a undefined" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", undefined) with attribute value "a b" (XML node with null namespace)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value "a" (foo node)]
+    expected: FAIL
+
+  [classList.replace("A", "b") with attribute value "a" (foo node)]
+    expected: FAIL
+
+  [classList.replace("b", "A") with attribute value "a b" (foo node)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b" (foo node)]
+    expected: FAIL
+
+  [classList.replace("d", "e") with attribute value "a b c" (foo node)]
+    expected: FAIL
+
+  [classList.replace("c", "d") with attribute value "a a a  b" (foo node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value null (foo node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value "" (foo node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " " (foo node)]
+    expected: FAIL
+
+  [classList.replace("a", "b") with attribute value " a  \\f" (foo node)]
+    expected: FAIL
+
+  [classList.replace("b", "d") with attribute value "a b c" (foo node)]
+    expected: FAIL
+
+  [classList.replace("c", "a") with attribute value "a b c" (foo node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "a b a" (foo node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "a b a" (foo node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "   a  a b" (foo node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "   a  a b" (foo node)]
+    expected: FAIL
+
+  [classList.replace("a", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (foo node)]
+    expected: FAIL
+
+  [classList.replace("b", "c") with attribute value "\\t\\n\\f\\r a\\t\\n\\f\\r b\\t\\n\\f\\r " (foo node)]
+    expected: FAIL
+
+  [classList.replace(null, "b") with attribute value "a null" (foo node)]
+    expected: FAIL
+
+  [classList.replace("a", null) with attribute value "a b" (foo node)]
+    expected: FAIL
+
+  [classList.replace(undefined, "b") with attribute value "a undefined" (foo node)]
+    expected: FAIL
+
+  [classList.replace("a", undefined) with attribute value "a b" (foo node)]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/fetch/api/response/response-error-from-stream.html.ini b/tests/wpt/metadata/fetch/api/response/response-error-from-stream.html.ini
new file mode 100644
index 00000000000..55576d655d7
--- /dev/null
+++ b/tests/wpt/metadata/fetch/api/response/response-error-from-stream.html.ini
@@ -0,0 +1,8 @@
+[response-error-from-stream.html]
+  expected: ERROR
+  [ReadableStreamDefaultReader Promise receives ReadableStream start() Error]
+    expected: FAIL
+
+  [ReadableStreamDefaultReader Promise receives ReadableStream pull() Error]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html.ini b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html.ini
new file mode 100644
index 00000000000..f263d01b825
--- /dev/null
+++ b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html.ini
@@ -0,0 +1,5 @@
+[iframe_sandbox_block_modals-2.html]
+  expected: TIMEOUT
+  [Frames without `allow-modals` should not be able to open modal dialogs]
+    expected: TIMEOUT
+
diff --git a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html.ini b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html.ini
new file mode 100644
index 00000000000..770c94d1294
--- /dev/null
+++ b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html.ini
@@ -0,0 +1,5 @@
+[iframe_sandbox_block_modals-3.html]
+  expected: TIMEOUT
+  [Frames without `allow-modals` should not be able to open modal dialogs]
+    expected: TIMEOUT
+
diff --git a/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html.ini b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html.ini
new file mode 100644
index 00000000000..9be138b347f
--- /dev/null
+++ b/tests/wpt/metadata/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html.ini
@@ -0,0 +1,5 @@
+[iframe_sandbox_block_modals-4.html]
+  expected: TIMEOUT
+  [Frames without `allow-modals` should not be able to open modal dialogs]
+    expected: TIMEOUT
+
diff --git a/tests/wpt/mozilla/meta/css/border_radius_elliptical_a.html.ini b/tests/wpt/mozilla/meta/css/border_radius_elliptical_a.html.ini
new file mode 100644
index 00000000000..ba813a41144
--- /dev/null
+++ b/tests/wpt/mozilla/meta/css/border_radius_elliptical_a.html.ini
@@ -0,0 +1,2 @@
+[border_radius_elliptical_a.html]
+  expected: FAIL
diff --git a/tests/wpt/mozilla/meta/css/iframe/hide_after_load.html.ini b/tests/wpt/mozilla/meta/css/iframe/hide_after_load.html.ini
deleted file mode 100644
index 65c78fd3a4a..00000000000
--- a/tests/wpt/mozilla/meta/css/iframe/hide_after_load.html.ini
+++ /dev/null
@@ -1,2 +0,0 @@
-[hide_after_load.html]
-  expected: TIMEOUT
diff --git a/tests/wpt/mozilla/meta/css/text_shadow_blur_a.html.ini b/tests/wpt/mozilla/meta/css/text_shadow_blur_a.html.ini
index 9ac9be5ac69..3ad8a9c02b5 100644
--- a/tests/wpt/mozilla/meta/css/text_shadow_blur_a.html.ini
+++ b/tests/wpt/mozilla/meta/css/text_shadow_blur_a.html.ini
@@ -1,4 +1,3 @@
 [text_shadow_blur_a.html]
   type: reftest
   expected: FAIL
-
diff --git a/tests/wpt/mozilla/meta/css/transition_calc_implicit.html.ini b/tests/wpt/mozilla/meta/css/transition_calc_implicit.html.ini
new file mode 100644
index 00000000000..dbea4f293ad
--- /dev/null
+++ b/tests/wpt/mozilla/meta/css/transition_calc_implicit.html.ini
@@ -0,0 +1,2 @@
+[transition_calc_implicit.html]
+  expected: TIMEOUT
diff --git a/tests/wpt/mozilla/meta/webgl/conformance-1.0.3/conformance/glsl/bugs/long-expressions-should-not-crash.html.ini b/tests/wpt/mozilla/meta/webgl/conformance-1.0.3/conformance/glsl/bugs/long-expressions-should-not-crash.html.ini
deleted file mode 100644
index 17dcfea137f..00000000000
--- a/tests/wpt/mozilla/meta/webgl/conformance-1.0.3/conformance/glsl/bugs/long-expressions-should-not-crash.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[long-expressions-should-not-crash.html]
-  expected: TIMEOUT
-  [Overall test]
-    expected: NOTRUN
-
diff --git a/tests/wpt/mozilla/meta/webgl/conformance-1.0.3/conformance/glsl/misc/shader-with-non-reserved-words.html.ini b/tests/wpt/mozilla/meta/webgl/conformance-1.0.3/conformance/glsl/misc/shader-with-non-reserved-words.html.ini
index c508ae3ae71..ad64e1afe0b 100644
--- a/tests/wpt/mozilla/meta/webgl/conformance-1.0.3/conformance/glsl/misc/shader-with-non-reserved-words.html.ini
+++ b/tests/wpt/mozilla/meta/webgl/conformance-1.0.3/conformance/glsl/misc/shader-with-non-reserved-words.html.ini
@@ -1,5 +1,6 @@
 [shader-with-non-reserved-words.html]
   type: testharness
+  expected: TIMEOUT
   [WebGL test #1696: shader with: 'dmat2' failed to compile]
     expected: FAIL
 
@@ -144,3 +145,6 @@
   [WebGL test #1862: shader with: 'dmat4x4' failed to compile]
     expected: FAIL
 
+  [Overall test]
+    expected: NOTRUN
+
diff --git a/tests/wpt/web-platform-tests/.travis.yml b/tests/wpt/web-platform-tests/.travis.yml
index 0a47a65f803..125d50bc2db 100644
--- a/tests/wpt/web-platform-tests/.travis.yml
+++ b/tests/wpt/web-platform-tests/.travis.yml
@@ -12,16 +12,11 @@ addons:
     - www2.web-platform.test
     - xn--n8j6ds53lwwkrqhv28a.web-platform.test
     - xn--lve-6lad.web-platform.test
-  jwt:
-    secure: N9lvgkqUPtFlz6Vpa6qTPFhymEsDCsbaCsT64/hj3vlHRxK94r5+ugVJ3zm99zC0q2j1ish8yJC7mN/W4wRfBE4sAwmdxrlowxF1DDGCkaLE9i/GWW92s0fBVGJmXLh8kwNkQ31hMOsaGfHIMpeLFS7Se741te7YqsHIzmBCdQs=
 before_install:
   # This needs be sourced as it sets various env vars
   - . ./tools/ci/before_install.sh
 install:
   - ./tools/ci/install.sh
-env:  # required at the top-level for allow_failures to work below
-  global:
-    - SAUCE_USERNAME=w3c-ttwf
 matrix:
   fast_finish: true
   include:
@@ -65,16 +60,6 @@ matrix:
       env:
         - secure: "YTSXPwI0DyCA1GhYrLT9KMEV6b7QQKuEeaQgeFDP38OTzJ1+cIj3CC4SRNqbnJ/6SJwPGcdqSxLuV8m4e5HFFnyCcQnJe6h8EMsTehZ7W3j/fP9UYrJqYqvGpe3Vj3xblO5pwBYmq7sg3jAmmuCgAgOW6VGf7cRMucrsmFeo7VM="
         - JOB=stability SCRIPT=tools/ci/ci_stability.sh PRODUCT=chrome:dev
-    - os: linux
-      python: "2.7"
-      env:
-        - secure: "YTSXPwI0DyCA1GhYrLT9KMEV6b7QQKuEeaQgeFDP38OTzJ1+cIj3CC4SRNqbnJ/6SJwPGcdqSxLuV8m4e5HFFnyCcQnJe6h8EMsTehZ7W3j/fP9UYrJqYqvGpe3Vj3xblO5pwBYmq7sg3jAmmuCgAgOW6VGf7cRMucrsmFeo7VM="
-        - JOB=stability SCRIPT=tools/ci/ci_stability.sh PRODUCT=sauce:safari:11.0 PLATFORM='macOS 10.12'
-    - os: linux
-      python: "2.7"
-      env:
-        - secure: "YTSXPwI0DyCA1GhYrLT9KMEV6b7QQKuEeaQgeFDP38OTzJ1+cIj3CC4SRNqbnJ/6SJwPGcdqSxLuV8m4e5HFFnyCcQnJe6h8EMsTehZ7W3j/fP9UYrJqYqvGpe3Vj3xblO5pwBYmq7sg3jAmmuCgAgOW6VGf7cRMucrsmFeo7VM="
-        - JOB=stability SCRIPT=tools/ci/ci_stability.sh PRODUCT=sauce:MicrosoftEdge:16.16299 PLATFORM='Windows 10'
     - python: 2.7
       env: JOB=tools_unittest TOXENV=py27 HYPOTHESIS_PROFILE=ci SCRIPT=tools/ci/ci_tools_unittest.sh
     - python: 3.6
@@ -105,12 +90,6 @@ matrix:
     - env:
         - secure: "YTSXPwI0DyCA1GhYrLT9KMEV6b7QQKuEeaQgeFDP38OTzJ1+cIj3CC4SRNqbnJ/6SJwPGcdqSxLuV8m4e5HFFnyCcQnJe6h8EMsTehZ7W3j/fP9UYrJqYqvGpe3Vj3xblO5pwBYmq7sg3jAmmuCgAgOW6VGf7cRMucrsmFeo7VM="
         - JOB=stability SCRIPT=tools/ci/ci_stability.sh PRODUCT=chrome:dev
-    - env:
-        - secure: "YTSXPwI0DyCA1GhYrLT9KMEV6b7QQKuEeaQgeFDP38OTzJ1+cIj3CC4SRNqbnJ/6SJwPGcdqSxLuV8m4e5HFFnyCcQnJe6h8EMsTehZ7W3j/fP9UYrJqYqvGpe3Vj3xblO5pwBYmq7sg3jAmmuCgAgOW6VGf7cRMucrsmFeo7VM="
-        - JOB=stability SCRIPT=tools/ci/ci_stability.sh PRODUCT=sauce:MicrosoftEdge:16.16299 PLATFORM='Windows 10'
-    - env:
-        - secure: "YTSXPwI0DyCA1GhYrLT9KMEV6b7QQKuEeaQgeFDP38OTzJ1+cIj3CC4SRNqbnJ/6SJwPGcdqSxLuV8m4e5HFFnyCcQnJe6h8EMsTehZ7W3j/fP9UYrJqYqvGpe3Vj3xblO5pwBYmq7sg3jAmmuCgAgOW6VGf7cRMucrsmFeo7VM="
-        - JOB=stability SCRIPT=tools/ci/ci_stability.sh PRODUCT=sauce:safari:11.0 PLATFORM='macOS 10.12'
 script:
   - ./tools/ci/run.sh
 cache:
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptor/gen-characteristic-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptor/gen-characteristic-is-removed.https.html
index c4c80d2e455..02aaeccb022 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptor/gen-characteristic-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptor/gen-characteristic-is-removed.https.html
@@ -17,7 +17,6 @@ bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(() => characteristic.getDescriptor(user_description.name))
     .then(() => null, (e) => assert_unreached('Caught error unexpectedly.', e))
     .then(() => fake_characteristic.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
       characteristic.getDescriptor(user_description.name), expected)),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptor/gen-service-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptor/gen-service-is-removed.https.html
index 0f1b514eb32..bfb4c8dcf6a 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptor/gen-service-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptor/gen-service-is-removed.https.html
@@ -17,7 +17,6 @@ let characteristic, fake_peripheral, fake_service;
 bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(_ => ({characteristic, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         characteristic.getDescriptor(user_description.name),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed-with-uuid.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed-with-uuid.https.html
index 1f675c866ba..c00d4cf5783 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed-with-uuid.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed-with-uuid.https.html
@@ -17,7 +17,6 @@ bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(() => characteristic.getDescriptor(user_description.name))
     .then(() => null, (e) => assert_unreached('Caught error unexpectedly.', e))
     .then(() => fake_characteristic.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
       characteristic.getDescriptors(user_description.name), expected)),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed.https.html
index 835036ffd42..a29548f3656 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed.https.html
@@ -17,7 +17,6 @@ bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(() => characteristic.getDescriptor(user_description.name))
     .then(() => null, (e) => assert_unreached('Caught error unexpectedly.', e))
     .then(() => fake_characteristic.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
       characteristic.getDescriptors(), expected)),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-service-is-removed-with-uuid.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-service-is-removed-with-uuid.https.html
index 6e697041f39..de83400b208 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-service-is-removed-with-uuid.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-service-is-removed-with-uuid.https.html
@@ -17,7 +17,6 @@ let characteristic, fake_peripheral, fake_service;
 bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(_ => ({characteristic, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         characteristic.getDescriptors(user_description.uuid),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-service-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-service-is-removed.https.html
index 8261511e8d2..c9056dd3b3c 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-service-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/getDescriptors/gen-service-is-removed.https.html
@@ -17,7 +17,6 @@ let characteristic, fake_peripheral, fake_service;
 bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(_ => ({characteristic, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         characteristic.getDescriptors(user_description.name),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/notifications/service-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/notifications/service-is-removed.https.html
index 58495f45663..bf389ce5286 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/notifications/service-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/notifications/service-is-removed.https.html
@@ -14,7 +14,6 @@ let characteristic, fake_peripheral, fake_service;
 bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(_ => ({characteristic, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         characteristic.startNotifications(),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/readValue/gen-characteristic-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/readValue/gen-characteristic-is-removed.https.html
index f03b2817d02..a80bccfe469 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/readValue/gen-characteristic-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/readValue/gen-characteristic-is-removed.https.html
@@ -17,7 +17,6 @@ bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(() => characteristic.getDescriptor(user_description.name))
     .then(() => null, (e) => assert_unreached('Caught error unexpectedly.', e))
     .then(() => fake_characteristic.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
       characteristic.readValue(), expected)),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/readValue/service-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/readValue/service-is-removed.https.html
index 4c7db9eb78a..48f8127de83 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/readValue/service-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/readValue/service-is-removed.https.html
@@ -14,7 +14,6 @@ let characteristic, fake_peripheral, fake_service;
 bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(_ => ({characteristic, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         characteristic.readValue(),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/startNotifications/gen-characteristic-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/startNotifications/gen-characteristic-is-removed.https.html
index 50e1786fe82..d9a9594320d 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/startNotifications/gen-characteristic-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/startNotifications/gen-characteristic-is-removed.https.html
@@ -17,7 +17,6 @@ bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(() => characteristic.getDescriptor(user_description.name))
     .then(() => null, (e) => assert_unreached('Caught error unexpectedly.', e))
     .then(() => fake_characteristic.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
       characteristic.startNotifications(), expected)),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/writeValue/gen-characteristic-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/writeValue/gen-characteristic-is-removed.https.html
index 72527ac86fe..16520704630 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/writeValue/gen-characteristic-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/writeValue/gen-characteristic-is-removed.https.html
@@ -17,7 +17,6 @@ bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(() => characteristic.getDescriptor(user_description.name))
     .then(() => null, (e) => assert_unreached('Caught error unexpectedly.', e))
     .then(() => fake_characteristic.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
       characteristic.writeValue(new Uint8Array(1)), expected)),
diff --git a/tests/wpt/web-platform-tests/bluetooth/characteristic/writeValue/service-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/characteristic/writeValue/service-is-removed.https.html
index a6101281178..2b43bfb7c91 100644
--- a/tests/wpt/web-platform-tests/bluetooth/characteristic/writeValue/service-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/characteristic/writeValue/service-is-removed.https.html
@@ -14,7 +14,6 @@ let characteristic, fake_peripheral, fake_service;
 bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(_ => ({characteristic, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         characteristic.writeValue(new ArrayBuffer(1 /* length */)),
diff --git a/tests/wpt/web-platform-tests/bluetooth/descriptor/readValue/gen-service-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/descriptor/readValue/gen-service-is-removed.https.html
index 46744642d70..e453c806374 100644
--- a/tests/wpt/web-platform-tests/bluetooth/descriptor/readValue/gen-service-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/descriptor/readValue/gen-service-is-removed.https.html
@@ -15,7 +15,6 @@ let descriptor, fake_peripheral, fake_service;
 bluetooth_test(() => getUserDescriptionDescriptor()
     .then(_ => ({descriptor, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         descriptor.readValue(),
diff --git a/tests/wpt/web-platform-tests/bluetooth/descriptor/writeValue/gen-service-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/descriptor/writeValue/gen-service-is-removed.https.html
index 849b45d3baa..acd56c3aa45 100644
--- a/tests/wpt/web-platform-tests/bluetooth/descriptor/writeValue/gen-service-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/descriptor/writeValue/gen-service-is-removed.https.html
@@ -15,7 +15,6 @@ let descriptor, fake_peripheral, fake_service;
 bluetooth_test(() => getUserDescriptionDescriptor()
     .then(_ => ({descriptor, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         descriptor.writeValue(new ArrayBuffer(1 /* length */)),
diff --git a/tests/wpt/web-platform-tests/bluetooth/script-tests/characteristic/characteristic-is-removed.js b/tests/wpt/web-platform-tests/bluetooth/script-tests/characteristic/characteristic-is-removed.js
index 5241ecf5d7e..8ff747c588d 100644
--- a/tests/wpt/web-platform-tests/bluetooth/script-tests/characteristic/characteristic-is-removed.js
+++ b/tests/wpt/web-platform-tests/bluetooth/script-tests/characteristic/characteristic-is-removed.js
@@ -9,7 +9,6 @@ bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(() => characteristic.getDescriptor(user_description.name))
     .then(() => null, (e) => assert_unreached('Caught error unexpectedly.', e))
     .then(() => fake_characteristic.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
       characteristic.CALLS([
diff --git a/tests/wpt/web-platform-tests/bluetooth/script-tests/characteristic/service-is-removed.js b/tests/wpt/web-platform-tests/bluetooth/script-tests/characteristic/service-is-removed.js
index 129a6db7af3..2f5824082b1 100644
--- a/tests/wpt/web-platform-tests/bluetooth/script-tests/characteristic/service-is-removed.js
+++ b/tests/wpt/web-platform-tests/bluetooth/script-tests/characteristic/service-is-removed.js
@@ -9,7 +9,6 @@ let characteristic, fake_peripheral, fake_service;
 bluetooth_test(() => getMeasurementIntervalCharacteristic()
     .then(_ => ({characteristic, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         characteristic.CALLS([
diff --git a/tests/wpt/web-platform-tests/bluetooth/script-tests/descriptor/service-is-removed.js b/tests/wpt/web-platform-tests/bluetooth/script-tests/descriptor/service-is-removed.js
index 17309630737..5373364399e 100644
--- a/tests/wpt/web-platform-tests/bluetooth/script-tests/descriptor/service-is-removed.js
+++ b/tests/wpt/web-platform-tests/bluetooth/script-tests/descriptor/service-is-removed.js
@@ -7,7 +7,6 @@ let descriptor, fake_peripheral, fake_service;
 bluetooth_test(() => getUserDescriptionDescriptor()
     .then(_ => ({descriptor, fake_peripheral, fake_service} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         descriptor.CALLS([
diff --git a/tests/wpt/web-platform-tests/bluetooth/script-tests/service/service-is-removed.js b/tests/wpt/web-platform-tests/bluetooth/script-tests/service/service-is-removed.js
index c1390fd88f7..aaf0f144367 100644
--- a/tests/wpt/web-platform-tests/bluetooth/script-tests/service/service-is-removed.js
+++ b/tests/wpt/web-platform-tests/bluetooth/script-tests/service/service-is-removed.js
@@ -8,7 +8,6 @@ let service, fake_service, fake_peripheral;
 bluetooth_test(() => getHealthThermometerService()
     .then(_ => ({service, fake_service, fake_peripheral} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         service.CALLS([
diff --git a/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristic/gen-service-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristic/gen-service-is-removed.https.html
index f056401cc57..391c49a0bab 100644
--- a/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristic/gen-service-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristic/gen-service-is-removed.https.html
@@ -16,7 +16,6 @@ let service, fake_service, fake_peripheral;
 bluetooth_test(() => getHealthThermometerService()
     .then(_ => ({service, fake_service, fake_peripheral} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         service.getCharacteristic('measurement_interval'),
diff --git a/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristics/gen-service-is-removed-with-uuid.https.html b/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristics/gen-service-is-removed-with-uuid.https.html
index 71b6d77a8ef..62caaad12b5 100644
--- a/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristics/gen-service-is-removed-with-uuid.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristics/gen-service-is-removed-with-uuid.https.html
@@ -16,7 +16,6 @@ let service, fake_service, fake_peripheral;
 bluetooth_test(() => getHealthThermometerService()
     .then(_ => ({service, fake_service, fake_peripheral} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         service.getCharacteristics('measurement_interval'),
diff --git a/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristics/gen-service-is-removed.https.html b/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristics/gen-service-is-removed.https.html
index 2bd7bf7934b..4868127465a 100644
--- a/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristics/gen-service-is-removed.https.html
+++ b/tests/wpt/web-platform-tests/bluetooth/service/getCharacteristics/gen-service-is-removed.https.html
@@ -16,7 +16,6 @@ let service, fake_service, fake_peripheral;
 bluetooth_test(() => getHealthThermometerService()
     .then(_ => ({service, fake_service, fake_peripheral} = _))
     .then(() => fake_service.remove())
-    .then(() => fake_peripheral.setNextGATTDiscoveryResponse({HCI_SUCCESS}))
     .then(() => fake_peripheral.simulateGATTServicesChanged())
     .then(() => assert_promise_rejects_with_message(
         service.getCharacteristics(),
diff --git a/tests/wpt/web-platform-tests/css/css-properties-values-api/register-property-syntax-parsing.html b/tests/wpt/web-platform-tests/css/css-properties-values-api/register-property-syntax-parsing.html
new file mode 100644
index 00000000000..500add40ef3
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-properties-values-api/register-property-syntax-parsing.html
@@ -0,0 +1,163 @@
+<!DOCTYPE HTML>
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#dom-css-registerproperty" />
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#supported-syntax-strings" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+test_count = 0;
+
+function assert_valid(syntax, initialValue) {
+    // No actual assertions, this just shouldn't throw
+    test(function() {
+        var name = '--syntax-test-' + (test_count++);
+        CSS.registerProperty({name: name, syntax: syntax, initialValue: initialValue});
+    }, "syntax:'" + syntax + "', initialValue:'" + initialValue + "' is valid");
+}
+
+function assert_invalid(syntax, initialValue) {
+    test(function(){
+        var name = '--syntax-test-' + (test_count++);
+        assert_throws(new SyntaxError(),
+            () => CSS.registerProperty({name: name, syntax: syntax, initialValue: initialValue}));
+    }, "syntax:'" + syntax + "', initialValue:'" + initialValue + "' is invalid");
+}
+
+assert_valid("*", "a");
+assert_valid(" * ", "b");
+assert_valid("<length>", "2px");
+assert_valid(" <number>", "5");
+assert_valid("<percentage> ", "10%");
+assert_valid("<color>+", "red");
+assert_valid(" <length>+ | <percentage>", "2px 8px");
+assert_valid("<length>|<percentage>|<length-percentage>", "2px"); // Valid but silly
+assert_valid("<color> | <image> | <url> | <integer> | <angle>", "red");
+assert_valid("<time> | <resolution> | <transform-list> | <custom-ident>", "red");
+
+assert_valid("*", ":> hello");
+assert_valid("*", "([ brackets ]) { yay (??)}");
+assert_valid("*", "yep 'this is valid too'");
+assert_valid("*", "unmatched opening bracket is valid :(");
+assert_valid("*", '"');
+
+assert_valid("<length>", "0");
+assert_valid("<length>", "10px /*:)*/");
+assert_valid("<length>", " calc(-2px)");
+assert_valid("<length>", "calc(2px*4 + 10px)");
+assert_valid("<length>", "7.1e-4cm");
+assert_valid("<length>", "calc(7in - 12px)");
+assert_valid("<length>+", "2px 7px calc(8px)");
+assert_valid("<percentage>", "-9.3e3%");
+assert_valid("<length-percentage>", "-54%");
+assert_valid("<length-percentage>", "0");
+assert_valid("<length-percentage>", "calc(-11px + 10.4%)");
+
+assert_valid("<number>", "-109");
+assert_valid("<number>", "2.3e4");
+assert_valid("<integer>", "-109");
+assert_valid("<integer>", "19");
+
+assert_valid("<angle>", "10deg");
+assert_valid("<angle>", "20.5rad");
+assert_valid("<angle>", "calc(50grad + 3.14159rad)");
+assert_valid("<time>", "2s");
+assert_valid("<time>", "calc(2s - 9ms)");
+assert_valid("<resolution>", "10dpi");
+assert_valid("<resolution>", "3dPpX");
+assert_valid("<resolution>", "-5.3dpcm");
+assert_valid("<transform-list>", "scale(2)");
+assert_valid("<transform-list>", "translateX(2px) rotate(20deg)");
+
+assert_valid("<color>", "rgb(12, 34, 56)");
+assert_valid("<color>", "lightgoldenrodyellow");
+assert_valid("<image>", "url(a)");
+assert_valid("<image>", "linear-gradient(yellow, blue)");
+assert_valid("<url>", "url(a)");
+
+assert_valid("banana", "banana");
+assert_valid("bAnAnA", "bAnAnA");
+assert_valid("ba-na-nya", "ba-na-nya");
+assert_valid("banana", "banan\\61");
+assert_valid("<custom-ident>", "banan\\61");
+assert_valid("big | bigger | BIGGER", "bigger");
+assert_valid("foo+|bar", "foo foo foo");
+assert_valid("default", "default");
+
+assert_valid("banana\t", "banana");
+assert_valid("\nbanana\r\n", "banana");
+assert_valid("ba\f\n|\tna\r|nya", "nya");
+
+assert_valid(null, "null");
+assert_valid(undefined, "undefined");
+assert_valid(["array"], "array");
+
+// Invalid syntax
+assert_invalid("banana,nya", "banana");
+assert_invalid("banan\\61", "banana");
+assert_invalid("<\\6c ength>", "10px");
+assert_invalid("<banana>", "banana");
+assert_invalid("<Number>", "10");
+assert_invalid("<length", "10px");
+assert_invalid("<LENGTH>", "10px");
+assert_invalid("< length>", "10px");
+assert_invalid("<length >", "10px");
+assert_invalid("<length> +", "10px");
+
+assert_invalid("<length>++", "10px");
+assert_invalid("<length> | *", "10px");
+assert_invalid("*|banana", "banana");
+assert_invalid("*+", "banana");
+
+assert_invalid("initial", "initial");
+assert_invalid("inherit", "inherit");
+assert_invalid("unset", "unset");
+assert_invalid("<length>|initial", "10px");
+assert_invalid("<length>|INHERIT", "10px");
+assert_invalid("<percentage>|unsEt", "2%");
+
+// Invalid initialValue
+assert_invalid("*", "initial");
+assert_invalid("*", "inherit");
+assert_invalid("*", "unset");
+assert_invalid("*", "revert");
+assert_invalid("<custom-ident>", "initial");
+assert_invalid("<custom-ident>+", "foo inherit bar");
+
+assert_invalid("*", ")");
+assert_invalid("*", "([)]");
+assert_invalid("*", "whee!");
+assert_invalid("*", '"\n');
+assert_invalid("*", "url(moo '')");
+assert_invalid("*", "semi;colon");
+assert_invalid("*", "var(invalid var ref)");
+assert_invalid("*", "var(--foo)");
+
+assert_invalid("banana", "bAnAnA");
+assert_invalid("<length>", "var(--moo)");
+assert_invalid("<length>", "10");
+assert_invalid("<length>", "10%");
+assert_invalid("<length>", "calc(5px + 10%)");
+assert_invalid("<length>", "calc(5px * 3px / 6px)");
+assert_invalid("<length>", "10em");
+assert_invalid("<length>", "10vmin");
+assert_invalid("<length>", "calc(4px + 3em)");
+assert_invalid("<length>", "calc(4px + calc(8 * 2em))");
+assert_invalid("<length>+", "calc(2ex + 16px)");
+assert_invalid("<length>+", "10px calc(20px + 4rem)");
+assert_invalid("<percentage> | <length>+", "calc(100vh - 10px) 30px");
+assert_invalid("<length>", "10px;");
+assert_invalid("<length-percentage>", "calc(2px + 10% + 7ex)");
+assert_invalid("<percentage>", "0");
+assert_invalid("<integer>", "1.0");
+assert_invalid("<integer>", "1e0");
+assert_invalid("<number>|foo", "foo var(--foo, bla)");
+
+assert_invalid("<angle>", "0");
+assert_invalid("<angle>", "10%");
+assert_invalid("<time>", "2px");
+assert_invalid("<resolution>", "10");
+assert_invalid("<transform-list>", "scale()");
+assert_invalid("<transform-list>+", "translateX(2px) rotate(20deg)");
+assert_invalid("<color>", "fancy-looking");
+assert_invalid("<image>", "banana.png");
+assert_invalid("<url>", "banana.png");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-properties-values-api/register-property.html b/tests/wpt/web-platform-tests/css/css-properties-values-api/register-property.html
new file mode 100644
index 00000000000..597247cc215
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-properties-values-api/register-property.html
@@ -0,0 +1,42 @@
+<!DOCTYPE HTML>
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#register-a-custom-property" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+// Tests for error checking during property registration
+
+test(function() {
+    assert_throws(new TypeError(), () => CSS.registerProperty());
+    assert_throws(new TypeError(), () => CSS.registerProperty(undefined));
+    assert_throws(new TypeError(), () => CSS.registerProperty(true));
+    assert_throws(new TypeError(), () => CSS.registerProperty(2));
+    assert_throws(new TypeError(), () => CSS.registerProperty("css"));
+    assert_throws(new TypeError(), () => CSS.registerProperty(null));
+}, "registerProperty requires a Dictionary type");
+
+test(function() {
+    // Valid property names, shouldn't throw
+    CSS.registerProperty({name: '--name1'});
+    CSS.registerProperty({name: '--name2, no need for escapes'});
+    CSS.registerProperty({name: ['--name', 3]});
+
+    // Invalid property names
+    assert_throws(new TypeError(), () => CSS.registerProperty({}));
+    assert_throws(new SyntaxError(), () => CSS.registerProperty({name: 'no-leading-dash'}));
+    assert_throws(new SyntaxError(), () => CSS.registerProperty({name: ''}));
+    assert_throws(new SyntaxError(), () => CSS.registerProperty({name: '\\--name'}));
+}, "registerProperty requires a name matching <custom-property-name>");
+
+test(function() {
+    CSS.registerProperty({name: '--syntax-test-1', syntax: '*'});
+    CSS.registerProperty({name: '--syntax-test-2', syntax: ' * '});
+    assert_throws(new SyntaxError(),
+        () => CSS.registerProperty({name: '--syntax-test-3', syntax: 'length'}));
+}, "registerProperty only allows omitting initialValue is syntax is '*'");
+
+test(function() {
+    CSS.registerProperty({name: '--re-register', syntax: '<length>', initialValue: '0px'});
+    assert_throws({name: 'InvalidModificationError'},
+        () => CSS.registerProperty({name: '--re-register', syntax: '<percentage>', initialValue: '0%'}));
+}, "registerProperty fails for an already registered property");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-properties-inheritance.html b/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-properties-inheritance.html
new file mode 100644
index 00000000000..17074a69619
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-properties-inheritance.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#dom-propertydescriptor-inherits" />
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#register-a-custom-property" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+#outer {
+    --inherited-length-1: 10px;
+    --inherited-length-2: var(--non-inherited-length-1);
+    --inherited-length-3: 30px;
+    --non-inherited-length-1: 22px;
+    --non-inherited-length-3: calc(var(--non-inherited-length-2) * 10);
+}
+
+#inner {
+    --inherited-length-3: 15px;
+    --non-inherited-length-1: 40px;
+    --non-inherited-length-2: 90px;
+}
+</style>
+<div id=outer><div id=inner></div></div>
+<script>
+CSS.registerProperty({name: '--inherited-length-1', syntax: '<length>', initialValue: '1px', inherits: true});
+CSS.registerProperty({name: '--inherited-length-2', syntax: '<length>', initialValue: '2px', inherits: true});
+CSS.registerProperty({name: '--inherited-length-3', syntax: '<length>', initialValue: '3px', inherits: true});
+CSS.registerProperty({name: '--non-inherited-length-1', syntax: '<length>', initialValue: '4px'});
+CSS.registerProperty({name: '--non-inherited-length-2', syntax: '<length>', initialValue: '5px'});
+CSS.registerProperty({name: '--non-inherited-length-3', syntax: '<length>', initialValue: '6px'});
+
+test(function() {
+    outerComputedStyle = getComputedStyle(outer);
+    assert_equals(outerComputedStyle.getPropertyValue('--inherited-length-1'), '10px');
+    assert_equals(outerComputedStyle.getPropertyValue('--inherited-length-2'), '22px');
+    assert_equals(outerComputedStyle.getPropertyValue('--inherited-length-3'), '30px');
+    assert_equals(outerComputedStyle.getPropertyValue('--non-inherited-length-1'), '22px');
+    assert_equals(outerComputedStyle.getPropertyValue('--non-inherited-length-2'), '5px');
+    assert_equals(outerComputedStyle.getPropertyValue('--non-inherited-length-3'), '50px');
+
+    innerComputedStyle = getComputedStyle(inner);
+    assert_equals(innerComputedStyle.getPropertyValue('--inherited-length-1'), '10px');
+    assert_equals(innerComputedStyle.getPropertyValue('--inherited-length-2'), '22px');
+    assert_equals(innerComputedStyle.getPropertyValue('--inherited-length-3'), '15px');
+    assert_equals(innerComputedStyle.getPropertyValue('--non-inherited-length-1'), '40px');
+    assert_equals(innerComputedStyle.getPropertyValue('--non-inherited-length-2'), '90px');
+    assert_equals(innerComputedStyle.getPropertyValue('--non-inherited-length-3'), '6px');
+}, "Registered properties are correctly inherited (or not) depending on the inherits flag.");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-property-computation.html b/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-property-computation.html
new file mode 100644
index 00000000000..8f635e97a63
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-property-computation.html
@@ -0,0 +1,88 @@
+<!DOCTYPE HTML>
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#calculation-of-computed-values" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+#divWithFontSizeSet, #parentDiv {
+    font-size: 10px;
+}
+#divWithFontSizeSet, #divWithFontSizeInherited {
+    --length-1: 12px;
+    --length-2: 13vw;
+    --length-3: 14em;
+    --length-4: 15vmin;
+    --length-5: calc(16px - 7em + 10vh);
+    --length-6: var(--length-3);
+    --length-percentage-1: 17em;
+    --length-percentage-2: 18%;
+    --length-percentage-3: calc(19em - 2%);
+    --list-1: 10px 3em;
+    --list-2: 4em 9px;
+    --list-3: 3% 10vmax 22px;
+    --list-4: calc(50% + 1em) 4px;
+}
+#fontSizeCycle {
+    --font-size: 2em;
+    font-size: var(--font-size);
+}
+</style>
+
+<div id=divWithFontSizeSet></div>
+<div id=parentDiv>
+    <div id=divWithFontSizeInherited></div>
+    <div id=fontSizeCycle></div>
+</div>
+
+<script>
+CSS.registerProperty({name: '--length-1', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--length-2', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--length-3', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--length-4', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--length-5', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--length-6', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--length-percentage-1', syntax: '<length-percentage>', initialValue: '0px'});
+CSS.registerProperty({name: '--length-percentage-2', syntax: '<length-percentage>', initialValue: '0px'});
+CSS.registerProperty({name: '--length-percentage-3', syntax: '<length-percentage>', initialValue: '0px'});
+CSS.registerProperty({name: '--list-1', syntax: '<length>+', initialValue: '0px'});
+CSS.registerProperty({name: '--list-2', syntax: '<length>+', initialValue: '0px'});
+CSS.registerProperty({name: '--list-3', syntax: '<length-percentage>+', initialValue: '0px'});
+CSS.registerProperty({name: '--list-4', syntax: '<length-percentage>+', initialValue: '0px'});
+CSS.registerProperty({name: '--font-size', syntax: '<length>', initialValue: '0px'});
+
+for (var element of [divWithFontSizeSet, divWithFontSizeInherited]) {
+    var id = element.id;
+    var computedStyle = getComputedStyle(element);
+
+    test(function() {
+        assert_equals(computedStyle.getPropertyValue('--length-1'), '12px');
+        assert_equals(computedStyle.getPropertyValue('--length-2'), '104px');
+        assert_equals(computedStyle.getPropertyValue('--length-3'), '140px');
+        assert_equals(computedStyle.getPropertyValue('--length-4'), '90px');
+        assert_equals(computedStyle.getPropertyValue('--length-5'), '6px');
+        assert_equals(computedStyle.getPropertyValue('--length-6'), '140px');
+    }, "<length> values are computed correctly for " + id);
+
+    test(function() {
+        assert_equals(computedStyle.getPropertyValue('--length-percentage-1'), '170px');
+        assert_equals(computedStyle.getPropertyValue('--length-percentage-2'), '18%');
+        assert_equals(computedStyle.getPropertyValue('--length-percentage-3'), 'calc(190px + -2%)');
+    }, "<length-percentage> values are computed correctly for " + id);
+
+    test(function() {
+        assert_equals(computedStyle.getPropertyValue('--list-1'), '10px 30px');
+        assert_equals(computedStyle.getPropertyValue('--list-2'), '40px 9px');
+    }, "<length>+ values are computed correctly for " + id);
+
+    test(function() {
+        assert_equals(computedStyle.getPropertyValue('--list-3'), '3% 80px 22px');
+        assert_equals(computedStyle.getPropertyValue('--list-4'), 'calc(10px + 50%) 4px');
+    }, "<length-percentage>+ values are computed correctly for " + id);
+}
+
+test(function() {
+    var computedStyle = getComputedStyle(fontSizeCycle);
+    assert_equals(computedStyle.fontSize, '20px');
+    assert_equals(computedStyle.getPropertyValue('--font-size'), '40px');
+}, "font-size with a var() reference to a registered property using ems works as expected");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-property-cssom.html b/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-property-cssom.html
new file mode 100644
index 00000000000..9dc9d7e50bb
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-property-cssom.html
@@ -0,0 +1,86 @@
+<!DOCTYPE HTML>
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#dom-css-registerproperty" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+#inner {
+  --length: 10px;
+  --color: red;
+}
+#outer {
+  --length: 77px;
+  --color: blue;
+}
+</style>
+
+<div id=outer>
+  <div id=inner></div>
+</div>
+
+<script>
+var computedStyle = getComputedStyle(inner);
+var inlineStyle = inner.style;
+var sheetStyle = document.styleSheets[0].cssRules[0].style;
+
+test(function() {
+  // Nothing registered yet, whatever you specify works
+  assert_equals(computedStyle.getPropertyValue('--length'), ' 10px');
+  assert_equals(computedStyle.getPropertyValue('--color'), ' red');
+
+  inlineStyle.setProperty('--length', '5');
+  inlineStyle.setProperty('--color', 'hello');
+
+  assert_equals(inlineStyle.getPropertyValue('--length'), '5');
+  assert_equals(inlineStyle.getPropertyValue('--color'), 'hello');
+  assert_equals(computedStyle.getPropertyValue('--length'), '5');
+  assert_equals(computedStyle.getPropertyValue('--color'), 'hello');
+}, "CSSOM setters function as expected for unregistered properties");
+
+CSS.registerProperty({name: '--length', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--color', syntax: '<color>', initialValue: 'white', inherits: true});
+
+test(function() {
+  assert_equals(inlineStyle.getPropertyValue('--length'), '5');
+  assert_equals(inlineStyle.getPropertyValue('--color'), 'hello');
+  assert_equals(computedStyle.getPropertyValue('--length'), '0px');
+  assert_equals(computedStyle.getPropertyValue('--color'), 'blue');
+}, "Formerly valid values are still readable from inline styles but are computed as the unset value");
+
+test(function() {
+  inlineStyle.setProperty('--length', 'hi');
+  inlineStyle.setProperty('--color', '20');
+  assert_equals(inlineStyle.getPropertyValue('--length'), '5');
+  assert_equals(inlineStyle.getPropertyValue('--color'), 'hello');
+}, "Values not matching the registered type can't be set");
+
+test(function() {
+  inlineStyle.removeProperty('--length');
+  inlineStyle.setProperty('--color', '');
+  assert_equals(inlineStyle.getPropertyValue('--length'), '');
+  assert_equals(inlineStyle.getPropertyValue('--color'), '');
+  assert_equals(computedStyle.getPropertyValue('--length'), '10px');
+  assert_equals(computedStyle.getPropertyValue('--color'), 'red');
+}, "Values can be removed from inline styles");
+
+test(function() {
+  sheetStyle.setProperty('--length', 'banana'); // Invalid, no change
+  assert_equals(computedStyle.getPropertyValue('--length'), '10px');
+  sheetStyle.setProperty('--length', '20px');
+  assert_equals(computedStyle.getPropertyValue('--length'), '20px');
+  sheetStyle.setProperty('--length', 'initial');
+  assert_equals(computedStyle.getPropertyValue('--length'), '0px');
+}, "Stylesheets can be modified by CSSOM");
+
+test(function() {
+  inlineStyle.setProperty('--length', '30px');
+  inlineStyle.setProperty('--color', 'pink');
+  assert_equals(inlineStyle.getPropertyValue('--length'), '30px');
+  assert_equals(inlineStyle.getPropertyValue('--color'), 'pink');
+  assert_equals(computedStyle.getPropertyValue('--length'), '30px');
+  assert_equals(computedStyle.getPropertyValue('--color'), 'pink');
+  inlineStyle.setProperty('--color', 'inherit');
+  assert_equals(inlineStyle.getPropertyValue('--color'), 'inherit');
+  assert_equals(computedStyle.getPropertyValue('--color'), 'blue');
+}, "Valid values can be set on inline styles");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-property-initial.html b/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-property-initial.html
new file mode 100644
index 00000000000..22ea3c4dd6b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-properties-values-api/registered-property-initial.html
@@ -0,0 +1,33 @@
+<!DOCTYPE HTML>
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#dom-propertydescriptor-initialvalue" />
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#register-a-custom-property" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+#target {
+  background: var(--inherited-color);
+  color: var(--non-inherited-color);
+}
+</style>
+<div id=target></div>
+<script>
+CSS.registerProperty({name: '--length', syntax: '<length>', initialValue: 'calc(10px + 15px)'});
+CSS.registerProperty({name: '--length-percentage', syntax: '<length-percentage>', initialValue: 'calc(1in + 10% + 4px)'});
+CSS.registerProperty({name: '--inherited-color', syntax: '<color>', initialValue: 'pink', inherits: true});
+CSS.registerProperty({name: '--non-inherited-color', syntax: '<color>', initialValue: 'purple'});
+CSS.registerProperty({name: '--single-transform-list', syntax: '<transform-list>', initialValue: 'scale(calc(2 + 2))'});
+CSS.registerProperty({name: '--multiple-transform-list', syntax: '<transform-list>', initialValue: 'scale(calc(2 + 1)) translateX(calc(3px + 1px))'});
+
+test(function() {
+    computedStyle = getComputedStyle(target);
+    assert_equals(computedStyle.getPropertyValue('--length'), '25px');
+    assert_equals(computedStyle.getPropertyValue('--length-percentage'), 'calc(100px + 10%)');
+    assert_equals(computedStyle.getPropertyValue('--inherited-color'), 'pink');
+    assert_equals(computedStyle.getPropertyValue('--non-inherited-color'), 'purple');
+    assert_equals(computedStyle.getPropertyValue('--single-transform-list'), 'scale(4)');
+    assert_equals(computedStyle.getPropertyValue('--multiple-transform-list'), 'scale(3) translateX(4px)');
+
+    assert_equals(computedStyle.backgroundColor, 'rgb(255, 192, 203)');
+    assert_equals(computedStyle.color, 'rgb(128, 0, 128)');
+}, "Initial values of registered properties can be referenced when no custom properties are explicitly set.");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-properties-values-api/var-reference-registered-properties-cycles.html b/tests/wpt/web-platform-tests/css/css-properties-values-api/var-reference-registered-properties-cycles.html
new file mode 100644
index 00000000000..fdf8eaae153
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-properties-values-api/var-reference-registered-properties-cycles.html
@@ -0,0 +1,145 @@
+<!DOCTYPE HTML>
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#dom-css-registerproperty" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<style>
+#test1 {
+    --registered-1-a: var(--registered-1-b, 10px);
+    --registered-1-b: var(--registered-1-a, 20px);
+
+    --registered-1-c: var(--registered-1-b, 30px);
+    --registered-1-d: var(--registered-1-b);
+    --unregistered-1-a:var(--registered-1-a,40px);
+    --unregistered-1-a:var(--registered-1-a);
+    left: var(--registered-1-a, 50px);
+    top: var(--registered-1-b, 60px);
+}
+</style>
+<div id=test1></div>
+<script>
+test(function() {
+    CSS.registerProperty({name: '--registered-1-a', syntax: '<length>', initialValue: '1px'});
+    CSS.registerProperty({name: '--registered-1-b', syntax: '<length>', initialValue: '2px'});
+    CSS.registerProperty({name: '--registered-1-c', syntax: '<length>', initialValue: '3px'});
+    CSS.registerProperty({name: '--registered-1-d', syntax: '<length>', initialValue: '4px'});
+
+    computedStyle = getComputedStyle(test1);
+    assert_equals(computedStyle.getPropertyValue('--registered-1-a'), '1px');
+    assert_equals(computedStyle.getPropertyValue('--registered-1-b'), '2px');
+
+    assert_equals(computedStyle.getPropertyValue('--registered-1-c'), '2px');
+    assert_equals(computedStyle.getPropertyValue('--registered-1-d'), '2px');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-1-a'), '1px');
+    assert_equals(computedStyle.left, '1px');
+    assert_equals(computedStyle.top, '2px');
+}, "A var() cycle between two registered properties is handled correctly.");
+</script>
+
+<style>
+#test2 {
+    --registered-2-a: var(--unregistered-2-a, 10px);
+    --unregistered-2-a:var(--registered-2-a,20px);
+
+    --registered-2-b: var(--registered-2-a, 30px);
+    --registered-2-c: var(--registered-2-a);
+    --registered-2-d: var(--unregistered-2-a, 40px);
+    --registered-2-e: var(--unregistered-2-a);
+    --unregistered-2-b:var(--registered-2-a,50px);
+    --unregistered-2-c:var(--registered-2-a);
+    --unregistered-2-d:var(--unregistered-2-a,60px);
+    --unregistered-2-e:var(--unregistered-2-a);
+    left: var(--registered-2-a, 70px);
+    top: var(--unregistered-2-a, 80px);
+}
+</style>
+<div id=test2></div>
+<script>
+test(function() {
+    CSS.registerProperty({name: '--registered-2-a', syntax: '<length>', initialValue: '1px'});
+    CSS.registerProperty({name: '--registered-2-b', syntax: '<length>', initialValue: '2px'});
+    CSS.registerProperty({name: '--registered-2-c', syntax: '<length>', initialValue: '3px'});
+    CSS.registerProperty({name: '--registered-2-d', syntax: '<length>', initialValue: '4px'});
+    CSS.registerProperty({name: '--registered-2-e', syntax: '<length>', initialValue: '5px'});
+
+    computedStyle = getComputedStyle(test2);
+    assert_equals(computedStyle.getPropertyValue('--registered-2-a'), '1px');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-2-a'), '');
+
+    assert_equals(computedStyle.getPropertyValue('--registered-2-b'), '1px');
+    assert_equals(computedStyle.getPropertyValue('--registered-2-c'), '1px');
+    assert_equals(computedStyle.getPropertyValue('--registered-2-d'), '40px');
+    assert_equals(computedStyle.getPropertyValue('--registered-2-e'), '5px');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-2-b'), '1px');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-2-c'), '1px');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-2-d'), '60px');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-2-e'), '');
+    assert_equals(computedStyle.left, '1px');
+    assert_equals(computedStyle.top, '80px');
+}, "A var() cycle between a registered properties and an unregistered property is handled correctly.");
+</script>
+
+<style>
+#test3 {
+    --unregistered-3-a:var(--unregistered-3-b,10px);
+    --unregistered-3-b:var(--unregistered-3-a,20px);
+
+    --registered-3-a: var(--unregistered-3-a, 30px);
+    --registered-3-b: var(--unregistered-3-a);
+    --registered-3-c: var(--unregistered-3-b, 40px);
+    --registered-3-d: var(--registered-3-c, 50px);
+    left: var(--registered-3-d, 60px);
+    top: var(--registered-3-b, 70px);
+}
+</style>
+<div id=test3></div>
+<script>
+test(function() {
+    CSS.registerProperty({name: '--registered-3-a', syntax: '<length>', initialValue: '1px'});
+    CSS.registerProperty({name: '--registered-3-b', syntax: '<length>', initialValue: '2px'});
+    CSS.registerProperty({name: '--registered-3-c', syntax: '<length>', initialValue: '3px'});
+    CSS.registerProperty({name: '--registered-3-d', syntax: '<length>', initialValue: '4px'});
+
+    computedStyle = getComputedStyle(test3);
+    assert_equals(computedStyle.getPropertyValue('--unregistered-3-a'), '');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-3-b'), '');
+
+    assert_equals(computedStyle.getPropertyValue('--registered-3-a'), '30px');
+    assert_equals(computedStyle.getPropertyValue('--registered-3-b'), '2px');
+    assert_equals(computedStyle.getPropertyValue('--registered-3-c'), '40px');
+    assert_equals(computedStyle.getPropertyValue('--registered-3-d'), '40px');
+    assert_equals(computedStyle.left, '40px');
+    assert_equals(computedStyle.top, '2px');
+}, "A var() cycle between a two unregistered properties is handled correctly.");
+</script>
+
+<style>
+#test4 {
+    --registered-4-a:var(--unregistered-4-a,hello);
+    --unregistered-4-a:var(--registered-4-a,world);
+
+    --registered-4-b:var(--unregistered-4-a,meow);
+    --registered-4-c:var(--unregistered-4-a);
+    --unregistered-4-b:var(--unregistered-4-a,woof);
+    --unregistered-4-c:var(--unregistered-4-a);
+    transition-property: var(--registered-4-a, water);
+}
+</style>
+<div id=test4></div>
+<script>
+test(function() {
+    CSS.registerProperty({name: '--registered-4-a', syntax: '*'});
+    CSS.registerProperty({name: '--registered-4-b', syntax: '*', initialValue: 'moo'});
+    CSS.registerProperty({name: '--registered-4-c', syntax: '*', initialValue: 'circle'});
+
+    computedStyle = getComputedStyle(test4);
+    assert_equals(computedStyle.getPropertyValue('--registered-4-a'), '');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-4-a'), '');
+
+    assert_equals(computedStyle.getPropertyValue('--registered-4-b'), 'meow');
+    assert_equals(computedStyle.getPropertyValue('--registered-4-c'), 'circle');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-4-b'), 'woof');
+    assert_equals(computedStyle.getPropertyValue('--unregistered-4-c'), '');
+    assert_equals(computedStyle.transitionProperty, 'water');
+}, "A var() cycle between a syntax:'*' property and an unregistered property is handled correctly.");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-properties-values-api/var-reference-registered-properties.html b/tests/wpt/web-platform-tests/css/css-properties-values-api/var-reference-registered-properties.html
new file mode 100644
index 00000000000..5dd1f0f1692
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-properties-values-api/var-reference-registered-properties.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api/#dom-css-registerproperty" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+div {
+    --registered-length-1: 10px;
+    --registered-length-2: var(--registered-length-1);
+    --registered-length-3: var(--length-1);
+    --registered-length-4: calc(var(--length-1) + 40px);
+    --registered-length-5: var(--invalid, 70px);
+    --registered-length-6: calc(var(--registered-length-3)*4);
+    --registered-length-7: var(--123px, 6px);
+
+    --length-1: 20px;
+    --length-2: var(--registered-length-1);
+    --length-3: calc(var(--123px, 6px) + var(--123px));
+
+    --percentage: 10%;
+    --registered-length-invalid: var(--percentage);
+
+    --registered-token-stream-1:var(--invalid);
+    --registered-token-stream-2:var(--invalid,fallback);
+    --token-stream-1:var(--registered-token-stream-1,moo);
+}
+</style>
+<div id=element></div>
+<script>
+CSS.registerProperty({name: '--123px', syntax: '<length>', initialValue: '123px'});
+
+CSS.registerProperty({name: '--registered-length-1', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--registered-length-2', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--registered-length-3', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--registered-length-4', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--registered-length-5', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--registered-length-6', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--registered-length-7', syntax: '<length>', initialValue: '0px'});
+CSS.registerProperty({name: '--registered-length-invalid', syntax: '<length>', initialValue: '15px'});
+
+CSS.registerProperty({name: '--registered-token-stream-1', syntax: '*'});
+CSS.registerProperty({name: '--registered-token-stream-2', syntax: '*'});
+
+test(function() {
+    computedStyle = getComputedStyle(element);
+    assert_equals(computedStyle.getPropertyValue('--registered-length-1'), '10px');
+    assert_equals(computedStyle.getPropertyValue('--registered-length-2'), '10px');
+    assert_equals(computedStyle.getPropertyValue('--registered-length-3'), '20px');
+    assert_equals(computedStyle.getPropertyValue('--registered-length-4'), '60px');
+    assert_equals(computedStyle.getPropertyValue('--registered-length-5'), '70px');
+    assert_equals(computedStyle.getPropertyValue('--registered-length-6'), '80px');
+    assert_equals(computedStyle.getPropertyValue('--registered-length-7'), '123px');
+    assert_equals(computedStyle.getPropertyValue('--length-1'), ' 20px');
+    assert_equals(computedStyle.getPropertyValue('--length-2'), '  10px');
+    assert_equals(computedStyle.getPropertyValue('--length-3'), ' calc(123px + 123px)');
+    assert_equals(computedStyle.getPropertyValue('--registered-length-invalid'), '15px');
+
+    assert_equals(computedStyle.getPropertyValue('--registered-token-stream-1'), '');
+    assert_equals(computedStyle.getPropertyValue('--registered-token-stream-2'), 'fallback');
+    assert_equals(computedStyle.getPropertyValue('--token-stream-1'), 'moo');
+}, "var() references work with registered properties");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-values/calc-in-color-001.html b/tests/wpt/web-platform-tests/css/css-values/calc-in-color-001.html
index e87719b4fe7..7db087def75 100644
--- a/tests/wpt/web-platform-tests/css/css-values/calc-in-color-001.html
+++ b/tests/wpt/web-platform-tests/css/css-values/calc-in-color-001.html
@@ -12,7 +12,8 @@ const TESTS = {
   // specified -> expected
   "rgb(calc(0), calc(255 + 0), calc(140 - 139 - 1))": "rgb(0, 255, 0)",
   "rgba(calc(0%) calc(100%) calc(0%) / calc(10% * 10))": "rgb(0, 255, 0)",
-  "hsl(calc(5deg * (360 / 5)), calc(10% * 10), calc(10% * 10))": "rgb(255, 255, 255)"
+  "hsl(calc(5deg * (360 / 5)), calc(10% * 10), calc(10% * 10))": "rgb(255, 255, 255)",
+  "hsla(calc(5 * (360 / 5)), calc(10% * 10), calc(10% * 10), calc(1.0))": "rgb(255, 255, 255)"
 }
 
 test(function() {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1-ref.html
index 43fa1caa6a1..ecd58d762f9 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1-ref.html
@@ -10,7 +10,7 @@
         width: 72px;
         height: 72px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-size: 36px 36px;
         background-repeat: repeat;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1a.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1a.html
index 7ba2329d93c..6717ce1b348 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1a.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1a.html
@@ -13,7 +13,7 @@
         width: 72px;
         height: 72px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: round;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1b.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1b.html
index 126909c906f..b3e1e9684b8 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1b.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1b.html
@@ -13,7 +13,7 @@
         width: 72px;
         height: 72px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: round round;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1c.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1c.html
index e956e16a49c..3fcfd80b1c7 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1c.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1c.html
@@ -14,7 +14,7 @@
         height: 72px;
         border: 1px solid black;
         background-size: 36px 36px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: repeat round;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1d.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1d.html
index 424c9590100..69045cf605a 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1d.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1d.html
@@ -14,7 +14,7 @@
         height: 72px;
         border: 1px solid black;
         background-size: 32px 36px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: round repeat;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1e.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1e.html
index 64640ffdcaa..5fd4973dcd8 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1e.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-1e.html
@@ -14,7 +14,7 @@
         height: 72px;
         border: 1px solid black;
         background-size: 36px 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: repeat round;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-2-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-2-ref.html
index 6d62330786f..b530e61a6b5 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-2-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-2-ref.html
@@ -10,7 +10,7 @@
       width: 72px;
       height: 72px;
       border: 1px solid black;
-      background-image: url(aqua-yellow-32x32.png);
+      background-image: url(support/aqua-yellow-32x32.png);
       background-size: 36px 36px;
       background-repeat: repeat-x;
     }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-2.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-2.html
index cdb85833cbb..702931abe84 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-2.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-2.html
@@ -13,7 +13,7 @@
       width: 72px;
       height: 72px;
       border: 1px solid black;
-      background-image: url(aqua-yellow-32x32.png);
+      background-image: url(support/aqua-yellow-32x32.png);
       background-repeat: round no-repeat;
     }
     .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-3-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-3-ref.html
index 49eaccb19ee..e44cecd8f5c 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-3-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-3-ref.html
@@ -10,7 +10,7 @@
         width: 72px;
         height: 72px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-size: 36px 36px;
         background-repeat: repeat-y;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-3.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-3.html
index 410d7ed67b1..c3b5e2b2d00 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-3.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-3.html
@@ -13,7 +13,7 @@
         width: 72px;
         height: 72px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-size: 36px auto;
         background-repeat: no-repeat round;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-4-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-4-ref.html
index 8bb7d709527..8139ace8dad 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-4-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-4-ref.html
@@ -10,7 +10,7 @@
         width: 72px;
         height: 72px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-size: 36px 36px;
         background-repeat: repeat;
         background-position: 5px 5px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-4.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-4.html
index f02ad55ab5d..be1a4c8ae9c 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-4.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-round-4.html
@@ -13,7 +13,7 @@
         width: 72px;
         height: 72px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: round;
         background-position: 5px 5px;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1-ref.html
index f9efeeb8395..11ea2c7bc1e 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1-ref.html
@@ -20,7 +20,7 @@
       {
         height: 32px;
         width: 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
       }
       .outer_gradient
       {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-10-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-10-ref.html
index 35ed461c8d7..f4c2b7c18e2 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-10-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-10-ref.html
@@ -20,7 +20,7 @@
       {
         height: 32px;
         width: 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
       }
     </style>
   </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-10.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-10.html
index db8c910d725..00205a938b8 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-10.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-10.html
@@ -13,7 +13,7 @@
         width: 96px;
         height: 106px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: space;
       }
     </style>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1a.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1a.html
index 3729e5ccb78..e4376c6391d 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1a.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1a.html
@@ -13,7 +13,7 @@
         width: 106px;
         height: 106px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: space;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1b.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1b.html
index 50efcc2536a..55bc6dc704d 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1b.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1b.html
@@ -13,7 +13,7 @@
         width: 106px;
         height: 106px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-position: 15px 15px;
         background-repeat: space;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1c.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1c.html
index 263bb0c2348..27470f9e0c0 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1c.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-1c.html
@@ -13,7 +13,7 @@
         width: 106px;
         height: 106px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: space space;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-2-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-2-ref.html
index c2fc93aaca0..5dbd30d550a 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-2-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-2-ref.html
@@ -10,7 +10,7 @@
         width: 48px;
         height: 48px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: no-repeat;
         background-position: 5px 5px;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-2.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-2.html
index 6099aa0c1b6..ac9664482c5 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-2.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-2.html
@@ -13,7 +13,7 @@
         width: 48px;
         height: 48px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: space;
         background-position: 5px 5px;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-3-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-3-ref.html
index add80bc3c42..f132f2eceac 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-3-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-3-ref.html
@@ -18,7 +18,7 @@
       {
         height: 32px;
         width: 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         margin-top: 40px;
       }
       .outer2
@@ -34,7 +34,7 @@
       {
         height: 32px;
         width: 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         margin-left: 40px;
       }
       .inner_gradient1
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-3.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-3.html
index 39d5701ecfa..9ea709b81f3 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-3.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-3.html
@@ -17,14 +17,14 @@
       .inner1 {
         width: 106px;
         height: 106px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: space no-repeat;
         background-position: 7px 40px;
       }
       .inner2 {
         width: 106px;
         height: 106px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: no-repeat space;
         background-position: 40px 7px;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-4-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-4-ref.html
index e7814de81c1..a375db50cd0 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-4-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-4-ref.html
@@ -19,7 +19,7 @@
       {
         height: 32px;
         width: 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
       }
       .inner_gradient
       {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-4.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-4.html
index c8be103d9d9..834381c76fe 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-4.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-4.html
@@ -13,7 +13,7 @@
         width: 96px;
         height: 106px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: repeat space;
       }
       .outer_graident {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-5-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-5-ref.html
index 9ff6c6e2dd3..d9d3ca11842 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-5-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-5-ref.html
@@ -19,7 +19,7 @@
       {
         height: 32px;
         width: 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
       }
       .inner_gradient
       {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-5.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-5.html
index 3c1b3d2d12c..0beca23d964 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-5.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-5.html
@@ -13,7 +13,7 @@
         width: 106px;
         height: 96px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: space repeat;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-6-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-6-ref.html
index 7e2f19c8dbe..c07440184b6 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-6-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-6-ref.html
@@ -19,7 +19,7 @@
       {
         height: 32px;
         width: 64px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: no-repeat;
         background-size: 64px 32px;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-6.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-6.html
index 50753522995..ae2c0fa8f63 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-6.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-6.html
@@ -14,7 +14,7 @@
         height: 106px;
         border: 1px solid black;
         background-size: 60px 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: round space;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-7-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-7-ref.html
index 528599004c9..541fbd4ddc2 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-7-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-7-ref.html
@@ -19,7 +19,7 @@
       {
         height: 64px;
         width: 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: no-repeat;
         background-size: 32px 64px;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-7.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-7.html
index 49bee1fec05..809875f57be 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-7.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-7.html
@@ -14,7 +14,7 @@
         height: 192px;
         border: 1px solid black;
         background-size: 32px 60px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: space round;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-8-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-8-ref.html
index 1f7f39e3594..58464091713 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-8-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-8-ref.html
@@ -11,7 +11,7 @@
         border: 20px solid rgba(0, 0, 0, 0.5);
         width: 106px;
         height: 106px;
-        background-image: url(aqua-yellow-37x37.png);
+        background-image: url(support/aqua-yellow-37x37.png);
         background-repeat: repeat;
       }
       .outer_gradient
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-8.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-8.html
index 0ad57afd9d1..473d115ba69 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-8.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-8.html
@@ -13,7 +13,7 @@
         width: 106px;
         height: 106px;
         border: 20px solid rgba(0, 0, 0, .5);
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: space;
       }
       .outer_gradient {
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-9-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-9-ref.html
index 1476eca646f..6aa9c732155 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-9-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-9-ref.html
@@ -20,7 +20,7 @@
       {
         height: 32px;
         width: 32px;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
       }
     </style>
   </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-9.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-9.html
index 66f6c225890..28ff46473be 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-9.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/background-repeat-space-9.html
@@ -13,7 +13,7 @@
         width: 106px;
         height: 96px;
         border: 1px solid black;
-        background-image: url(aqua-yellow-32x32.png);
+        background-image: url(support/aqua-yellow-32x32.png);
         background-repeat: space;
       }
     </style>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-1-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-1-ref.html
index 69d38c3179d..298b46dd128 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-1-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-1-ref.html
@@ -16,7 +16,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner2 {
         position: absolute;
@@ -25,7 +25,7 @@
         width: 34px;
         height: 27px;
         background-size: 102px 81px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -34px 0px;
       }
       .inner3 {
@@ -34,7 +34,7 @@
         left: 61px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner4 {
         position: absolute;
@@ -43,7 +43,7 @@
         width: 27px;
         height: 34px;
         background-size: 81px 102px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: 0px -34px;
       }
       .inner5 {
@@ -53,7 +53,7 @@
         width: 27px;
         height: 34px;
         background-size: 81px 102px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -54px -34px;
       }
       .inner6 {
@@ -62,7 +62,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner7 {
         position: absolute;
@@ -71,7 +71,7 @@
         width: 34px;
         height: 27px;
         background-size: 102px 81px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -34px -54px;
       }
       .inner8 {
@@ -80,7 +80,7 @@
         left: 61px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
     </style>
     </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-1.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-1.html
index a935e445f57..832126ef3df 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-1.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-1.html
@@ -14,7 +14,7 @@
         left: 0px;
         top: 0px;
         border: 27px solid transparent;
-        border-image: url("border.png") 27;
+        border-image: url("support/border.png") 27;
         border-image-repeat: round round;
         width: 34px;
         height: 34px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-2-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-2-ref.html
index e96185c047a..e76f7cee832 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-2-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-2-ref.html
@@ -16,7 +16,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner2 {
         position: absolute;
@@ -25,7 +25,7 @@
         width: 13px;
         height: 27px;
         background-size: 39px 81px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -13px 0px;
       }
       .inner3 {
@@ -34,7 +34,7 @@
         left: 40px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner4 {
         position: absolute;
@@ -43,7 +43,7 @@
         width: 27px;
         height: 13px;
         background-size: 81px 39px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: 0px -13px;
       }
       .inner5 {
@@ -53,7 +53,7 @@
         width: 27px;
         height: 13px;
         background-size: 81px 39px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -54px -13px;
       }
       .inner6 {
@@ -62,7 +62,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner7 {
         position: absolute;
@@ -71,7 +71,7 @@
         width: 13px;
         height: 27px;
         background-size: 39px 81px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -13px -54px;
       }
       .inner8 {
@@ -80,7 +80,7 @@
         left: 40px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
     </style>
     </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-2.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-2.html
index 3c1cd3344bd..4e08ae03665 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-2.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-round-2.html
@@ -14,7 +14,7 @@
         left: 0px;
         top: 0px;
         border: 27px solid transparent;
-        border-image: url("border.png") 27;
+        border-image: url("support/border.png") 27;
         border-image-repeat: round round;
         width: 13px;
         height: 13px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-1-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-1-ref.html
index e2cc7105e77..7c6555a0ae4 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-1-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-1-ref.html
@@ -16,7 +16,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner2 {
         position: absolute;
@@ -24,7 +24,7 @@
         left: 31px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px 0px;
       }
       .inner3 {
@@ -33,7 +33,7 @@
         left: 62px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner4 {
         position: absolute;
@@ -41,7 +41,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: 0px -27px;
       }
       .inner5 {
@@ -50,7 +50,7 @@
         left: 62px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -54px -27px;
       }
       .inner6 {
@@ -59,7 +59,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner7 {
         position: absolute;
@@ -67,7 +67,7 @@
         left: 31px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px -54px;
       }
       .inner8 {
@@ -76,7 +76,7 @@
         left: 62px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
     </style>
     </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-1.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-1.html
index 113d000dff7..c186a3139fe 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-1.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-1.html
@@ -14,7 +14,7 @@
         left: 0px;
         top: 0px;
         border: 27px solid transparent;
-        border-image: url("border.png") 27;
+        border-image: url("support/border.png") 27;
         border-image-repeat: space space;
         width: 35px;
         height: 35px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-2-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-2-ref.html
index 17b83e18360..6afc0733880 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-2-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-2-ref.html
@@ -16,7 +16,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner2 {
         position: absolute;
@@ -24,7 +24,7 @@
         left: 40px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner3 {
         position: absolute;
@@ -32,7 +32,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner4 {
         position: absolute;
@@ -40,7 +40,7 @@
         left: 40px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
     </style>
     </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-2.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-2.html
index 99dc6057f8a..b38bc847342 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-2.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-2.html
@@ -14,7 +14,7 @@
         left: 0px;
         top: 0px;
         border: 27px solid transparent;
-        border-image: url("border.png") 27;
+        border-image: url("support/border.png") 27;
         border-image-repeat: space space;
         width: 13px;
         height: 13px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-3-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-3-ref.html
index 03c23018671..904b325ccdc 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-3-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-3-ref.html
@@ -16,7 +16,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner2_1 {
         position: absolute;
@@ -24,7 +24,7 @@
         left: 29px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px 0px;
       }
       .inner2_2 {
@@ -33,7 +33,7 @@
         left: 58px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px 0px;
       }
       .inner3 {
@@ -42,7 +42,7 @@
         left: 87px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner4_1 {
         position: absolute;
@@ -50,7 +50,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: 0px -27px;
       }
       .inner4_2 {
@@ -59,7 +59,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: 0px -27px;
       }
       .inner5_1 {
@@ -68,7 +68,7 @@
         left: 87px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -54px -27px;
       }
       .inner5_2 {
@@ -77,7 +77,7 @@
         left: 87px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -54px -27px;
       }
       .inner6 {
@@ -86,7 +86,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner7_1 {
         position: absolute;
@@ -94,7 +94,7 @@
         left: 29px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px -54px;
       }
       .inner7_2 {
@@ -103,7 +103,7 @@
         left: 58px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px -54px;
       }
       .inner8 {
@@ -112,7 +112,7 @@
         left: 87px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
     </style>
     </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-3.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-3.html
index c43f1d37025..085498f76a9 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-3.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-3.html
@@ -14,7 +14,7 @@
         left: 0px;
         top: 0px;
         border: 27px solid transparent;
-        border-image: url("border.png") 27;
+        border-image: url("support/border.png") 27;
         border-image-repeat: space space;
         width: 60px;
         height: 60px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4-ref-1.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4-ref-1.html
index 2cf40973942..ff7700e9af1 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4-ref-1.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4-ref-1.html
@@ -17,7 +17,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner2 {
         position: absolute;
@@ -25,7 +25,7 @@
         left: 27px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px 0px;
       }
       .inner3 {
@@ -34,7 +34,7 @@
         left: 54px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner4 {
         position: absolute;
@@ -42,7 +42,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: 0px -27px;
       }
       .inner5 {
@@ -51,7 +51,7 @@
         left: 54px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -54px -27px;
       }
       .inner6 {
@@ -60,7 +60,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner7 {
         position: absolute;
@@ -68,7 +68,7 @@
         left: 27px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px -54px;
       }
       .inner8 {
@@ -77,7 +77,7 @@
         left: 54px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
     </style>
     </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4-ref-2.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4-ref-2.html
index eee8c778745..dda3de638a2 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4-ref-2.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4-ref-2.html
@@ -11,7 +11,7 @@
         left: 0px;
         top: 0px;
         border: 27px solid transparent;
-        border-image: url("border.png") 27;
+        border-image: url("support/border.png") 27;
         border-image-repeat: stretch stretch;
         width: 27px;
         height: 27px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4.html
index b91e3abf851..d82969d71c4 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-4.html
@@ -14,7 +14,7 @@
         left: 0px;
         top: 0px;
         border: 27px solid transparent;
-        border-image: url("border.png") 27;
+        border-image: url("support/border.png") 27;
         border-image-repeat: space space;
         width: 27px;
         height: 27px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5-ref-1.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5-ref-1.html
index ac2fcea7f87..d52cab5bbe9 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5-ref-1.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5-ref-1.html
@@ -17,7 +17,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner2_1 {
         position: absolute;
@@ -25,7 +25,7 @@
         left: 27px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px 0px;
       }
       .inner2_2 {
@@ -34,7 +34,7 @@
         left: 54px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px 0px;
       }
       .inner2_3 {
@@ -43,7 +43,7 @@
         left: 81px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px 0px;
       }
       .inner3 {
@@ -52,7 +52,7 @@
         left: 108px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner4_1 {
         position: absolute;
@@ -60,7 +60,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: 0px -27px;
       }
       .inner4_2 {
@@ -69,7 +69,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: 0px -27px;
       }
       .inner4_3 {
@@ -78,7 +78,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: 0px -27px;
       }
       .inner5_1 {
@@ -87,7 +87,7 @@
         left: 108px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -54px -27px;
       }
       .inner5_2 {
@@ -96,7 +96,7 @@
         left: 108px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -54px -27px;
       }
       .inner5_3 {
@@ -105,7 +105,7 @@
         left: 108px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -54px -27px;
       }
       .inner6 {
@@ -114,7 +114,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
       .inner7_1 {
         position: absolute;
@@ -122,7 +122,7 @@
         left: 27px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px -54px;
       }
       .inner7_2 {
@@ -131,7 +131,7 @@
         left: 54px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px -54px;
       }
       .inner7_3 {
@@ -140,7 +140,7 @@
         left: 81px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
         background-position: -27px -54px;
       }
       .inner8 {
@@ -149,7 +149,7 @@
         left: 108px;
         width: 27px;
         height: 27px;
-        background-image: url("border.png");
+        background-image: url("support/border.png");
       }
     </style>
     </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5-ref-2.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5-ref-2.html
index 1d24b447e4c..bda8d7237f3 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5-ref-2.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5-ref-2.html
@@ -11,7 +11,7 @@
         left: 0px;
         top: 0px;
         border: 27px solid transparent;
-        border-image: url("border.png") 27;
+        border-image: url("support/border.png") 27;
         border-image-repeat: repeat repeat;
         width: 81px;
         height: 81px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5.html
index 582c6586113..db21548af86 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-5.html
@@ -14,7 +14,7 @@
         left: 0px;
         top: 0px;
         border: 27px solid transparent;
-        border-image: url("border.png") 27;
+        border-image: url("support/border.png") 27;
         border-image-repeat: space space;
         width: 81px;
         height: 81px;
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-6-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-6-ref.html
index 16647b3b724..307eda0ea52 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-6-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-6-ref.html
@@ -16,7 +16,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-tl.png");
+        background-image: url("support/reticule-tl.png");
       }
       .inner2 {
         position: absolute;
@@ -24,7 +24,7 @@
         left: 27px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-to.png");
+        background-image: url("support/reticule-to.png");
       }
       .inner3 {
         position: absolute;
@@ -32,7 +32,7 @@
         left: 54px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-tr.png");
+        background-image: url("support/reticule-tr.png");
       }
       .inner4 {
         position: absolute;
@@ -40,7 +40,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-le.png");
+        background-image: url("support/reticule-le.png");
       }
       .inner5 {
         position: absolute;
@@ -48,7 +48,7 @@
         left: 27px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-ct.png");
+        background-image: url("support/reticule-ct.png");
       }
       .inner6 {
         position: absolute;
@@ -56,7 +56,7 @@
         left: 54px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-ri.png");
+        background-image: url("support/reticule-ri.png");
       }
       .inner7 {
         position: absolute;
@@ -64,7 +64,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-bl.png");
+        background-image: url("support/reticule-bl.png");
       }
       .inner8 {
         position: absolute;
@@ -72,7 +72,7 @@
         left: 27px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-bo.png");
+        background-image: url("support/reticule-bo.png");
       }
       .inner9 {
         position: absolute;
@@ -80,7 +80,7 @@
         left: 54px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-br.png");
+        background-image: url("support/reticule-br.png");
       }
     </style>
     </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-6.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-6.html
index 3eb643110fb..045cde139d7 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-6.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-6.html
@@ -15,7 +15,7 @@
         top: 0px;
         border-width: 27px;
         border-style: solid;
-        border-image: url("reticule.png") 27 fill space;
+        border-image: url("support/reticule.png") 27 fill space;
         width: 27px;
         height: 27px;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-7-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-7-ref.html
index e0cbdfe2d04..44b07f7696a 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-7-ref.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-7-ref.html
@@ -16,7 +16,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-tl.png");
+        background-image: url("support/reticule-tl.png");
       }
       .inner2_1 {
         position: absolute;
@@ -24,7 +24,7 @@
         left: 35px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-to.png");
+        background-image: url("support/reticule-to.png");
       }
       .inner2_2 {
         position: absolute;
@@ -32,7 +32,7 @@
         left: 70px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-to.png");
+        background-image: url("support/reticule-to.png");
       }
       .inner3 {
         position: absolute;
@@ -40,7 +40,7 @@
         left: 105px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-tr.png");
+        background-image: url("support/reticule-tr.png");
       }
       .inner4_1 {
         position: absolute;
@@ -48,7 +48,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-le.png");
+        background-image: url("support/reticule-le.png");
       }
       .inner4_2 {
         position: absolute;
@@ -56,7 +56,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-le.png");
+        background-image: url("support/reticule-le.png");
       }
       .inner5_1 {
         position: absolute;
@@ -64,7 +64,7 @@
         left: 35px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-ct.png");
+        background-image: url("support/reticule-ct.png");
       }
       .inner5_2 {
         position: absolute;
@@ -72,7 +72,7 @@
         left: 70px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-ct.png");
+        background-image: url("support/reticule-ct.png");
       }
       .inner5_3 {
         position: absolute;
@@ -80,7 +80,7 @@
         left: 35px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-ct.png");
+        background-image: url("support/reticule-ct.png");
       }
       .inner5_4 {
         position: absolute;
@@ -88,7 +88,7 @@
         left: 70px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-ct.png");
+        background-image: url("support/reticule-ct.png");
       }
       .inner6_1 {
         position: absolute;
@@ -96,7 +96,7 @@
         left: 105px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-ri.png");
+        background-image: url("support/reticule-ri.png");
       }
       .inner6_2 {
         position: absolute;
@@ -104,7 +104,7 @@
         left: 105px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-ri.png");
+        background-image: url("support/reticule-ri.png");
       }
       .inner7 {
         position: absolute;
@@ -112,7 +112,7 @@
         left: 0px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-bl.png");
+        background-image: url("support/reticule-bl.png");
       }
       .inner8_1 {
         position: absolute;
@@ -120,7 +120,7 @@
         left: 35px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-bo.png");
+        background-image: url("support/reticule-bo.png");
       }
       .inner8_2 {
         position: absolute;
@@ -128,7 +128,7 @@
         left: 70px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-bo.png");
+        background-image: url("support/reticule-bo.png");
       }
       .inner9 {
         position: absolute;
@@ -136,7 +136,7 @@
         left: 105px;
         width: 27px;
         height: 27px;
-        background-image: url("reticule-br.png");
+        background-image: url("support/reticule-br.png");
       }
     </style>
     </head>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-7.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-7.html
index 3e632877dd8..367657858ea 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-7.html
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border-image-repeat-space-7.html
@@ -15,7 +15,7 @@
         top: 0px;
         border-width: 27px;
         border-style: solid;
-        border-image: url("reticule.png") 27 fill space;
+        border-image: url("support/reticule.png") 27 fill space;
         width: 78px;
         height: 78px;
       }
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-32x32.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/aqua-yellow-32x32.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-32x32.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/aqua-yellow-32x32.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-37x37.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/aqua-yellow-37x37.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-37x37.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/aqua-yellow-37x37.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/border.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/border.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/border.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-bl.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-bl.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-bl.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-bl.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-bo.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-bo.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-bo.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-bo.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-br.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-br.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-br.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-br.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-ct.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-ct.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-ct.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-ct.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-le.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-le.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-le.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-le.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-ri.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-ri.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-ri.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-ri.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-tl.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-tl.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-tl.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-tl.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-to.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-to.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-to.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-to.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-tr.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-tr.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-tr.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule-tr.png
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule.png b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule.png
similarity index 100%
rename from tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule.png
rename to tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/background/support/reticule.png
diff --git a/tests/wpt/web-platform-tests/dom/nodes/Element-classlist.html b/tests/wpt/web-platform-tests/dom/nodes/Element-classlist.html
index bc28b1c6678..2b376d4cb00 100644
--- a/tests/wpt/web-platform-tests/dom/nodes/Element-classlist.html
+++ b/tests/wpt/web-platform-tests/dom/nodes/Element-classlist.html
@@ -370,65 +370,66 @@ function testClassList(e, desc) {
 
 
   // replace() method
-  function checkReplace(before, token, newToken, after, expectedException) {
-    checkModification(e, "replace", [token, newToken], undefined, before,
+  function checkReplace(before, token, newToken, expectedRes, after, expectedException) {
+    checkModification(e, "replace", [token, newToken], expectedRes, before,
                       after, expectedException, desc);
   }
 
-  checkReplace(null, "", "a", null, "SyntaxError");
-  checkReplace(null, "", " ", null, "SyntaxError");
-  checkReplace(null, " ", "a", null, "InvalidCharacterError");
-  checkReplace(null, "\ta", "b", null, "InvalidCharacterError");
-  checkReplace(null, "a\t", "b", null, "InvalidCharacterError");
-  checkReplace(null, "\na", "b", null, "InvalidCharacterError");
-  checkReplace(null, "a\n", "b", null, "InvalidCharacterError");
-  checkReplace(null, "\fa", "b", null, "InvalidCharacterError");
-  checkReplace(null, "a\f", "b", null, "InvalidCharacterError");
-  checkReplace(null, "\ra", "b", null, "InvalidCharacterError");
-  checkReplace(null, "a\r", "b", null, "InvalidCharacterError");
-  checkReplace(null, " a", "b", null, "InvalidCharacterError");
-  checkReplace(null, "a ", "b", null, "InvalidCharacterError");
+  checkReplace(null, "", "a", null, null, "SyntaxError");
+  checkReplace(null, "", " ", null, null, "SyntaxError");
+  checkReplace(null, " ", "a", null, null, "InvalidCharacterError");
+  checkReplace(null, "\ta", "b", null, null, "InvalidCharacterError");
+  checkReplace(null, "a\t", "b", null, null, "InvalidCharacterError");
+  checkReplace(null, "\na", "b", null, null, "InvalidCharacterError");
+  checkReplace(null, "a\n", "b", null, null, "InvalidCharacterError");
+  checkReplace(null, "\fa", "b", null, null, "InvalidCharacterError");
+  checkReplace(null, "a\f", "b", null, null, "InvalidCharacterError");
+  checkReplace(null, "\ra", "b", null, null, "InvalidCharacterError");
+  checkReplace(null, "a\r", "b", null, null, "InvalidCharacterError");
+  checkReplace(null, " a", "b", null, null, "InvalidCharacterError");
+  checkReplace(null, "a ", "b", null, null, "InvalidCharacterError");
 
-  checkReplace(null, "a", "", null, "SyntaxError");
-  checkReplace(null, " ", "", null, "SyntaxError");
-  checkReplace(null, "a", " ", null, "InvalidCharacterError");
-  checkReplace(null, "b", "\ta", null, "InvalidCharacterError");
-  checkReplace(null, "b", "a\t", null, "InvalidCharacterError");
-  checkReplace(null, "b", "\na", null, "InvalidCharacterError");
-  checkReplace(null, "b", "a\n", null, "InvalidCharacterError");
-  checkReplace(null, "b", "\fa", null, "InvalidCharacterError");
-  checkReplace(null, "b", "a\f", null, "InvalidCharacterError");
-  checkReplace(null, "b", "\ra", null, "InvalidCharacterError");
-  checkReplace(null, "b", "a\r", null, "InvalidCharacterError");
-  checkReplace(null, "b", " a", null, "InvalidCharacterError");
-  checkReplace(null, "b", "a ", null, "InvalidCharacterError");
+  checkReplace(null, "a", "", null, null, "SyntaxError");
+  checkReplace(null, " ", "", null, null, "SyntaxError");
+  checkReplace(null, "a", " ", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", "\ta", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", "a\t", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", "\na", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", "a\n", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", "\fa", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", "a\f", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", "\ra", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", "a\r", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", " a", null, null, "InvalidCharacterError");
+  checkReplace(null, "b", "a ", null, null, "InvalidCharacterError");
 
-  checkReplace("a", "a", "a", "a");
-  checkReplace("a", "a", "b", "b");
-  checkReplace("a", "A", "b", "a");
-  checkReplace("a b", "b", "A", "a A");
-  checkReplace("a b c", "d", "e", "a b c");
+  checkReplace("a", "a", "a", true, "a");
+  checkReplace("a", "a", "b", true, "b");
+  checkReplace("a", "A", "b", false, "a");
+  checkReplace("a b", "b", "A", true, "a A");
+  checkReplace("a b", "c", "a", false, "a b");
+  checkReplace("a b c", "d", "e", false, "a b c");
   // https://github.com/whatwg/dom/issues/443
-  checkReplace("a a a  b", "a", "a", "a b");
-  checkReplace("a a a  b", "c", "d", "a a a  b");
-  checkReplace(null, "a", "b", null);
-  checkReplace("", "a", "b", "");
-  checkReplace(" ", "a", "b", " ");
-  checkReplace(" a  \f", "a", "b", "b");
-  checkReplace("a b c", "b", "d", "a d c");
-  checkReplace("a b c", "c", "a", "a b");
-  checkReplace("c b a", "c", "a", "a b");
-  checkReplace("a b a", "a", "c", "c b");
-  checkReplace("a b a", "b", "c", "a c");
-  checkReplace("   a  a b", "a", "c", "c b");
-  checkReplace("   a  a b", "b", "c", "a c");
-  checkReplace("\t\n\f\r a\t\n\f\r b\t\n\f\r ", "a", "c", "c b");
-  checkReplace("\t\n\f\r a\t\n\f\r b\t\n\f\r ", "b", "c", "a c");
+  checkReplace("a a a  b", "a", "a", true, "a b");
+  checkReplace("a a a  b", "c", "d", false, "a a a  b");
+  checkReplace(null, "a", "b", false, null);
+  checkReplace("", "a", "b", false, "");
+  checkReplace(" ", "a", "b", false, " ");
+  checkReplace(" a  \f", "a", "b", true, "b");
+  checkReplace("a b c", "b", "d", true, "a d c");
+  checkReplace("a b c", "c", "a", true, "a b");
+  checkReplace("c b a", "c", "a", true, "a b");
+  checkReplace("a b a", "a", "c", true, "c b");
+  checkReplace("a b a", "b", "c", true, "a c");
+  checkReplace("   a  a b", "a", "c", true, "c b");
+  checkReplace("   a  a b", "b", "c", true, "a c");
+  checkReplace("\t\n\f\r a\t\n\f\r b\t\n\f\r ", "a", "c", true, "c b");
+  checkReplace("\t\n\f\r a\t\n\f\r b\t\n\f\r ", "b", "c", true, "a c");
 
-  checkReplace("a null", null, "b", "a b");
-  checkReplace("a b", "a", null, "null b");
-  checkReplace("a undefined", undefined, "b", "a b");
-  checkReplace("a b", "a", undefined, "undefined b");
+  checkReplace("a null", null, "b", true, "a b");
+  checkReplace("a b", "a", null, true, "null b");
+  checkReplace("a undefined", undefined, "b", true, "a b");
+  checkReplace("a b", "a", undefined, true, "undefined b");
 }
 
 var content = document.getElementById("content");
diff --git a/tests/wpt/web-platform-tests/fetch/api/response/response-error-from-stream.html b/tests/wpt/web-platform-tests/fetch/api/response/response-error-from-stream.html
new file mode 100644
index 00000000000..392bc77a6c0
--- /dev/null
+++ b/tests/wpt/web-platform-tests/fetch/api/response/response-error-from-stream.html
@@ -0,0 +1,69 @@
+<!doctype html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>Response Receives Propagated Error from ReadableStream</title>
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+  </head>
+  <body>
+    <script>
+      function CustomTestError() {
+        const error = Error();
+        error.name = 'custom-test-error';
+        return error;
+      }
+
+      function newStreamWithStartError() {
+        return new ReadableStream({
+          start(controller) {
+            controller.error(CustomTestError());
+          }
+        })
+      }
+
+      function newStreamWithPullError() {
+        return new ReadableStream({
+          pull(controller) {
+            controller.error(CustomTestError());
+          }
+        })
+      }
+
+      function runRequestPromiseTest(stream, responseReaderMethod, testDescription) {
+        promise_test(test => {
+          return promise_rejects(
+            test,
+            CustomTestError(),
+            new Response(stream)[responseReaderMethod](),
+            'CustomTestError should propagate'
+          )
+        }, testDescription)
+      }
+
+
+      promise_test(test => {
+        return promise_rejects(test, CustomTestError(), newStreamWithStartError().getReader().read(), 'CustomTestError should propagate')
+      }, "ReadableStreamDefaultReader Promise receives ReadableStream start() Error")
+
+      promise_test(test => {
+        return promise_rejects(test, CustomTestError(), newStreamWithPullError().getReader().read(), 'CustomTestError should propagate')
+      }, "ReadableStreamDefaultReader Promise receives ReadableStream pull() Error")
+
+
+      // test start() errors for all Body reader methods
+      runRequestPromiseTest(newStreamWithStartError(), 'arrayBuffer', 'ReadableStream start() Error propagates to Response.arrayBuffer() Promise');
+      runRequestPromiseTest(newStreamWithStartError(), 'blob',        'ReadableStream start() Error propagates to Response.blob() Promise');
+      runRequestPromiseTest(newStreamWithStartError(), 'formData',    'ReadableStream start() Error propagates to Response.formData() Promise');
+      runRequestPromiseTest(newStreamWithStartError(), 'json',        'ReadableStream start() Error propagates to Response.json() Promise');
+      runRequestPromiseTest(newStreamWithStartError(), 'text',        'ReadableStream start() Error propagates to Response.text() Promise');
+
+      // test pull() errors for all Body reader methods
+      runRequestPromiseTest(newStreamWithPullError(), 'arrayBuffer', 'ReadableStream pull() Error propagates to Response.arrayBuffer() Promise');
+      runRequestPromiseTest(newStreamWithPullError(), 'blob',        'ReadableStream pull() Error propagates to Response.blob() Promise');
+      runRequestPromiseTest(newStreamWithPullError(), 'formData',    'ReadableStream pull() Error propagates to Response.formData() Promise');
+      runRequestPromiseTest(newStreamWithPullError(), 'json',        'ReadableStream pull() Error propagates to Response.json() Promise');
+      runRequestPromiseTest(newStreamWithPullError(), 'text',        'ReadableStream pull() Error propagates to Response.text() Promise');
+    </script>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-1.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-1.html
new file mode 100644
index 00000000000..ce171bfb8e1
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-1.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>iframe sandbox without allow_modals (alert)</title>
+<link rel="author" title="Igalia" href="https://www.igalia.com/">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#attr-iframe-sandbox">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#the-iframe-element">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe sandbox="allow-scripts"></iframe>
+<script src="support/iframe_sandbox_block_modals.js"></script>
+<script>
+    runTest("alert", undefined);
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html
new file mode 100644
index 00000000000..fbd4d23d015
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>iframe sandbox without allow_modals (confirm)</title>
+<link rel="author" title="Igalia" href="https://www.igalia.com/">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#attr-iframe-sandbox">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#the-iframe-element">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe sandbox="allow-scripts"></iframe>
+<script src="support/iframe_sandbox_block_modals.js"></script>
+<script>
+    runTest("confirm", false);
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html
new file mode 100644
index 00000000000..57123011807
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>iframe sandbox without allow_modals (prompt)</title>
+<link rel="author" title="Igalia" href="https://www.igalia.com/">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#attr-iframe-sandbox">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#the-iframe-element">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe sandbox="allow-scripts"></iframe>
+<script src="support/iframe_sandbox_block_modals.js"></script>
+<script>
+    runTest("prompt", null);
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html
new file mode 100644
index 00000000000..f750e345ea3
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>iframe sandbox without allow_modals (print)</title>
+<link rel="author" title="Igalia" href="https://www.igalia.com/">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#attr-iframe-sandbox">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#the-iframe-element">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe sandbox="allow-scripts"></iframe>
+<script src="support/iframe_sandbox_block_modals.js"></script>
+<script>
+    runTest("print", undefined);
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/support/iframe-that-opens-modals.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/support/iframe-that-opens-modals.html
new file mode 100644
index 00000000000..50f56c6278a
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/support/iframe-that-opens-modals.html
@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<script>
+function openModal(name) {
+    switch (name) {
+    case "alert":
+        return alert("MESSAGE");
+    break;
+    case "confirm":
+        return confirm("MESSAGE?");
+    break;
+    case "prompt":
+        return prompt("MESSAGE:", "DEFAULT VALUE");
+    break;
+    case "print":
+        return print();
+    break;
+  }
+}
+
+onmessage = function(e) {
+    parent.postMessage(openModal(e.data), "*");
+}
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/support/iframe_sandbox_block_modals.js b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/support/iframe_sandbox_block_modals.js
new file mode 100644
index 00000000000..67733d8101b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/support/iframe_sandbox_block_modals.js
@@ -0,0 +1,18 @@
+function runTest(modalName, expectedValue) {
+    let timeOutForFailingToOpenModal = 500;
+    let startTime;
+    async_test(t => {
+        let iframe = document.querySelector("iframe");
+        iframe.onload = t.step_func(() => {
+            window.addEventListener("message", t.step_func_done(e => {
+                // This tests work by checking the call to open the modal diaglog will return immediately (or at least within timeOutForFailingToOpenModal).
+                // If the modal dialog is not blocked, then it will wait for user input and the test will time out.
+                assert_less_than(new Date().getTime() - startTime, timeOutForFailingToOpenModal, "Call to open modal dialog did not return immediately");
+                assert_equals(e.data, expectedValue, "Call to open modal dialog did not return expected value");
+            }));
+            startTime = new Date().getTime();
+            iframe.contentWindow.postMessage(modalName, "*");
+        });
+        iframe.src = "support/iframe-that-opens-modals.html";
+    }, "Frames without `allow-modals` should not be able to open modal dialogs");
+}
diff --git a/tests/wpt/web-platform-tests/interfaces/dom.idl b/tests/wpt/web-platform-tests/interfaces/dom.idl
index e97f803f821..ae65018c71b 100644
--- a/tests/wpt/web-platform-tests/interfaces/dom.idl
+++ b/tests/wpt/web-platform-tests/interfaces/dom.idl
@@ -548,7 +548,7 @@ interface DOMTokenList {
   [CEReactions] void add(DOMString... tokens);
   [CEReactions] void remove(DOMString... tokens);
   [CEReactions] boolean toggle(DOMString token, optional boolean force);
-  [CEReactions] void replace(DOMString token, DOMString newToken);
+  [CEReactions] boolean replace(DOMString token, DOMString newToken);
   boolean supports(DOMString token);
   [CEReactions] stringifier attribute DOMString value;
   //  iterable<DOMString>;
diff --git a/tests/wpt/web-platform-tests/lint.whitelist b/tests/wpt/web-platform-tests/lint.whitelist
index 032303aeca1..74ecc09bf41 100644
--- a/tests/wpt/web-platform-tests/lint.whitelist
+++ b/tests/wpt/web-platform-tests/lint.whitelist
@@ -403,19 +403,6 @@ SUPPORT-WRONG-DIR: css/filter-effects/filter-external-002-filter.svg
 SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/check-for-references.sh
 SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/sync-tests-filter
 SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/sync-tests.sh
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-32x32.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/aqua-yellow-37x37.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/border.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-bl.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-bo.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-br.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-ct.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-le.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-ri.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-tl.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-to.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule-tr.png
-SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/background/reticule.png
 SUPPORT-WRONG-DIR: css/vendor-imports/mozilla/mozilla-central-reftests/masking/blank.html
 SUPPORT-WRONG-DIR: css/WOFF2/testcaseindex.xht
 NON-EXISTENT-REF: css/css-masking/clip-path-svg-content/clip-path-clip-rule-008.svg
diff --git a/tests/wpt/web-platform-tests/sensors/generic-sensor-tests.js b/tests/wpt/web-platform-tests/sensors/generic-sensor-tests.js
index 4be4841586d..86ce7fe1f39 100644
--- a/tests/wpt/web-platform-tests/sensors/generic-sensor-tests.js
+++ b/tests/wpt/web-platform-tests/sensors/generic-sensor-tests.js
@@ -13,6 +13,14 @@ const properties = {
                          'accuracy', 'altitudeAccuracy', 'heading', 'speed'],
   'ProximitySensor' : ['timestamp', 'max']
 };
+const spatialSensors = ['Accelerometer',
+                       'LinearAccelerationSensor',
+                       'GravitySensor',
+                       'Gyroscope',
+                       'Magnetometer',
+                       'UncalibratedMagnetometer',
+                       'AbsoluteOrientationSensor',
+                       'RelativeOrientationSensor'];
 
 function assert_reading_not_null(sensor) {
   for (let property in properties[sensor.constructor.name]) {
@@ -242,6 +250,24 @@ function runGenericSensorTests(sensorType) {
     sensor.stop();
   }, `${sensorType.name}: sensor receives suspend / resume notifications when\
   cross-origin subframe is focused`);
+
+  if (spatialSensors.indexOf(sensorType.name) == -1) {
+    // The sensorType does not represent a spatial sensor.
+    return;
+  }
+
+  promise_test(async t => {
+    const sensor = new sensorType({referenceFrame: "screen"});
+    const sensorWatcher = new EventWatcher(t, sensor, ["reading", "error"]);
+    sensor.start();
+
+    await sensorWatcher.wait_for("reading");
+    //TODO use mock data to verify sensor readings, blocked by issue:
+    // https://github.com/w3c/web-platform-tests/issues/9686
+    assert_reading_not_null(sensor);
+
+    sensor.stop();
+  }, `${sensorType.name}: sensor reading is correct when options.referenceFrame is 'screen'`);
 }
 
 function runGenericSensorInsecureContext(sensorType) {
diff --git a/tests/wpt/web-platform-tests/tools/ci/check_stability.py b/tests/wpt/web-platform-tests/tools/ci/check_stability.py
index 322a52140a2..fb9988dc96c 100644
--- a/tests/wpt/web-platform-tests/tools/ci/check_stability.py
+++ b/tests/wpt/web-platform-tests/tools/ci/check_stability.py
@@ -172,22 +172,6 @@ def get_parser():
     return parser
 
 
-def set_default_args(kwargs):
-    kwargs.set_if_none("sauce_platform",
-                       os.environ.get("PLATFORM"))
-    kwargs.set_if_none("sauce_build",
-                       os.environ.get("TRAVIS_BUILD_NUMBER"))
-    python_version = os.environ.get("TRAVIS_PYTHON_VERSION")
-    kwargs.set_if_none("sauce_tags",
-                       [python_version] if python_version else [])
-    kwargs.set_if_none("sauce_tunnel_id",
-                       os.environ.get("TRAVIS_JOB_NUMBER"))
-    kwargs.set_if_none("sauce_user",
-                       os.environ.get("SAUCE_USERNAME"))
-    kwargs.set_if_none("sauce_key",
-                       os.environ.get("SAUCE_ACCESS_KEY"))
-
-
 def pr():
     pr = os.environ.get("TRAVIS_PULL_REQUEST", "false")
     return pr if pr != "false" else None
@@ -301,10 +285,6 @@ def run(venv, wpt_args, **kwargs):
 
     browser_name = wpt_args.product.split(":")[0]
 
-    if browser_name == "sauce" and not wpt_args.sauce_key:
-        logger.warning("Cannot run tests on Sauce Labs. No access key.")
-        return retcode
-
     pr_number = pr()
 
     with TravisFold("browser_setup"):
@@ -338,8 +318,6 @@ def run(venv, wpt_args, **kwargs):
 
             wpt_kwargs["test_list"] = list(tests_changed | files_affected)
 
-        set_default_args(wpt_kwargs)
-
         do_delayed_imports()
 
         wpt_kwargs["stability"] = True
diff --git a/tests/wpt/web-platform-tests/tools/wpt/browser.py b/tests/wpt/web-platform-tests/tools/wpt/browser.py
index 04a4104c186..5dfcfa55727 100644
--- a/tests/wpt/web-platform-tests/tools/wpt/browser.py
+++ b/tests/wpt/web-platform-tests/tools/wpt/browser.py
@@ -444,8 +444,37 @@ class Servo(Browser):
     product = "servo"
     requirements = "requirements_servo.txt"
 
+    def platform_components(self):
+        platform = {
+            "Linux": "linux",
+            "Windows": "win",
+            "Darwin": "mac"
+        }.get(uname[0])
+
+        if platform is None:
+            raise ValueError("Unable to construct a valid Servo package for current platform")
+
+        if platform == "linux":
+            extension = ".tar.gz"
+            decompress = untar
+        elif platform == "win" or platform == "mac":
+            raise ValueError("Unable to construct a valid Servo package for current platform")
+
+        return (platform, extension, decompress)
+
     def install(self, dest=None):
-        raise NotImplementedError
+        """Install latest Browser Engine."""
+        if dest is None:
+            dest = os.pwd
+
+        platform, extension, decompress = self.platform_components()
+        url = "https://download.servo.org/nightly/%s/servo-latest%s" % (platform, extension)
+
+        decompress(get(url).raw, dest=dest)
+        path = find_executable("servo", os.path.join(dest, "servo"))
+        st = os.stat(path)
+        os.chmod(path, st.st_mode | stat.S_IEXEC)
+        return path
 
     def find_binary(self):
         return find_executable("servo")
@@ -457,7 +486,9 @@ class Servo(Browser):
         raise NotImplementedError
 
     def version(self, root):
-        return None
+        """Retrieve the release version of the installed browser."""
+        output = call(self.binary, "--version")
+        return re.search(r"[0-9\.]+( [a-z]+)?$", output.strip()).group(0)
 
 
 class Sauce(Browser):
diff --git a/tests/wpt/web-platform-tests/tools/wpt/run.py b/tests/wpt/web-platform-tests/tools/wpt/run.py
index d0a7925e79b..b9f5aadeea6 100644
--- a/tests/wpt/web-platform-tests/tools/wpt/run.py
+++ b/tests/wpt/web-platform-tests/tools/wpt/run.py
@@ -352,7 +352,8 @@ class Servo(BrowserSetup):
     browser_cls = browser.Servo
 
     def install(self, venv):
-        raise NotImplementedError
+        if self.prompt_install(self.name):
+            return self.browser.install(venv.path)
 
     def setup_kwargs(self, kwargs):
         if kwargs["binary"] is None:
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_chrome.txt b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_chrome.txt
index e2098cf59da..b5e48068722 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_chrome.txt
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_chrome.txt
@@ -1,2 +1,2 @@
 mozprocess == 0.26
-selenium==3.10.0
+selenium==3.11.0
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_chrome_android.txt b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_chrome_android.txt
index e2098cf59da..b5e48068722 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_chrome_android.txt
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_chrome_android.txt
@@ -1,2 +1,2 @@
 mozprocess == 0.26
-selenium==3.10.0
+selenium==3.11.0
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_edge.txt b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_edge.txt
index e2098cf59da..b5e48068722 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_edge.txt
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_edge.txt
@@ -1,2 +1,2 @@
 mozprocess == 0.26
-selenium==3.10.0
+selenium==3.11.0
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_ie.txt b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_ie.txt
index e2098cf59da..b5e48068722 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_ie.txt
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_ie.txt
@@ -1,2 +1,2 @@
 mozprocess == 0.26
-selenium==3.10.0
+selenium==3.11.0
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_opera.txt b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_opera.txt
index e2098cf59da..b5e48068722 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_opera.txt
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_opera.txt
@@ -1,2 +1,2 @@
 mozprocess == 0.26
-selenium==3.10.0
+selenium==3.11.0
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_safari.txt b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_safari.txt
index e2098cf59da..b5e48068722 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_safari.txt
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_safari.txt
@@ -1,2 +1,2 @@
 mozprocess == 0.26
-selenium==3.10.0
+selenium==3.11.0
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_sauce.txt b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_sauce.txt
index c076d75bac7..e0ae7e262c5 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/requirements_sauce.txt
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/requirements_sauce.txt
@@ -1,3 +1,3 @@
 mozprocess == 0.26
-selenium==3.10.0
+selenium==3.11.0
 requests==2.18.4
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/firefox.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/firefox.py
index 37da191dd44..e59cd90b0a3 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/firefox.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/firefox.py
@@ -304,12 +304,15 @@ class FirefoxBrowser(Browser):
 
     def on_output(self, line):
         """Write a line of output from the firefox process to the log"""
-        data = line.decode("utf8", "replace")
-        if self.stack_fixer:
-            data = self.stack_fixer(data)
-        self.logger.process_output(self.pid(),
-                                   data,
-                                   command=" ".join(self.runner.command))
+        if "GLib-GObject-CRITICAL" in line:
+            return
+        if line:
+            data = line.decode("utf8", "replace")
+            if self.stack_fixer:
+                data = self.stack_fixer(data)
+            self.logger.process_output(self.pid(),
+                                      data,
+                                      command=" ".join(self.runner.command))
 
     def is_alive(self):
         if self.runner: