diff --git a/tests/wpt/metadata/MANIFEST.json b/tests/wpt/metadata/MANIFEST.json
index ed9391e979a..5950afd55f2 100644
--- a/tests/wpt/metadata/MANIFEST.json
+++ b/tests/wpt/metadata/MANIFEST.json
@@ -289,6 +289,12 @@
      {}
     ]
    ],
+   "console/console-format-specifier-symbol-manual.html": [
+    [
+     "/console/console-format-specifier-symbol-manual.html",
+     {}
+    ]
+   ],
    "core-aam/alert-manual.html": [
     [
      "/core-aam/alert-manual.html",
@@ -48453,6 +48459,18 @@
      {}
     ]
    ],
+   "css/CSS2/floats/intrinsic-size-float-and-line.html": [
+    [
+     "/css/CSS2/floats/intrinsic-size-float-and-line.html",
+     [
+      [
+       "/css/reference/ref-filled-green-200px-square.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/CSS2/fonts/font-003.xht": [
     [
      "/css/CSS2/fonts/font-003.xht",
@@ -116321,6 +116339,30 @@
      {}
     ]
    ],
+   "css/css-layout-api/box-tree-registered.https.html": [
+    [
+     "/css/css-layout-api/box-tree-registered.https.html",
+     [
+      [
+       "/css/css-layout-api/box-tree-registered-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
+   "css/css-layout-api/box-tree-unregistered.https.html": [
+    [
+     "/css/css-layout-api/box-tree-unregistered.https.html",
+     [
+      [
+       "/css/css-layout-api/box-tree-unregistered-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/css-lists/counter-increment-inside-display-contents.html": [
     [
      "/css/css-lists/counter-increment-inside-display-contents.html",
@@ -125421,6 +125463,18 @@
      {}
     ]
    ],
+   "css/css-tables/internal-containing-block-001.html": [
+    [
+     "/css/css-tables/internal-containing-block-001.html",
+     [
+      [
+       "/css/reference/ref-filled-green-100px-square.xht",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/css-tables/visibility-collapse-colspan-003.html": [
     [
      "/css/css-tables/visibility-collapse-colspan-003.html",
@@ -160221,6 +160275,18 @@
      {}
     ]
    ],
+   "css/mediaqueries/viewport-script-dynamic.html": [
+    [
+     "/css/mediaqueries/viewport-script-dynamic.html",
+     [
+      [
+       "/css/mediaqueries/viewport-script-dynamic-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/motion/offset-anchor-transform-box-fill-box.html": [
     [
      "/css/motion/offset-anchor-transform-box-fill-box.html",
@@ -163341,6 +163407,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-horiz-001v.xhtml": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-horiz-001v.xhtml",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-horiz-001-ref.xhtml",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-vert-001.xhtml": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-vert-001.xhtml",
@@ -163353,6 +163431,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-vert-001v.xhtml": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-vert-001v.xhtml",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-vert-001-ref.xhtml",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-horiz-001.xhtml": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-horiz-001.xhtml",
@@ -163365,6 +163455,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-horiz-001v.xhtml": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-horiz-001v.xhtml",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-horiz-001-ref.xhtml",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-vert-001.xhtml": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-vert-001.xhtml",
@@ -163377,6 +163479,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-vert-001v.xhtml": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-vert-001v.xhtml",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-vert-001-ref.xhtml",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-fieldset-horiz-001.xhtml": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-fieldset-horiz-001.xhtml",
@@ -163725,6 +163839,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-001v.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-001v.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-001-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-002.html": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-002.html",
@@ -163737,6 +163863,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-002v.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-002v.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-001-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-003.html": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-003.html",
@@ -163749,6 +163887,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-003v.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-003v.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-003-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-004.html": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-004.html",
@@ -163761,6 +163911,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-004v.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-004v.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-004-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-005.html": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-005.html",
@@ -163773,6 +163935,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-005v.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-005v.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-005-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-006.html": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-006.html",
@@ -163785,6 +163959,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-006v.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-006v.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-006-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-items-as-stacking-contexts-001.xhtml": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-items-as-stacking-contexts-001.xhtml",
@@ -164061,6 +164247,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-002v.xhtml": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-002v.xhtml",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-002-ref.xhtml",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-003-reverse.xhtml": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-003-reverse.xhtml",
@@ -164085,6 +164283,18 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-003v.xhtml": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-003v.xhtml",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-003-ref.xhtml",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-004.xhtml": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-004.xhtml",
@@ -164697,6 +164907,78 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015.html": [
+    [
+     "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015.html",
+     [
+      [
+       "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/position-absolute-containing-block-001.html": [
     [
      "/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/position-absolute-containing-block-001.html",
@@ -211569,6 +211851,16 @@
      {}
     ]
    ],
+   "cookie-store/cookie-store.idl": [
+    [
+     {}
+    ]
+   ],
+   "cookie-store/idlharness_serviceworker.js": [
+    [
+     {}
+    ]
+   ],
    "cookie-store/resources/cookie-store-tests.js": [
     [
      {}
@@ -245619,6 +245911,16 @@
      {}
     ]
    ],
+   "css/css-layout-api/box-tree-registered-ref.html": [
+    [
+     {}
+    ]
+   ],
+   "css/css-layout-api/box-tree-unregistered-ref.html": [
+    [
+     {}
+    ]
+   ],
    "css/css-lists/OWNERS": [
     [
      {}
@@ -260209,6 +260511,11 @@
      {}
     ]
    ],
+   "css/mediaqueries/viewport-script-dynamic-ref.html": [
+    [
+     {}
+    ]
+   ],
    "css/motion/animation/resources/interpolation-testcommon.js": [
     [
      {}
@@ -264164,6 +264471,36 @@
      {}
     ]
    ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010-ref.html": [
+    [
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011-ref.html": [
+    [
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012-ref.html": [
+    [
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013-ref.html": [
+    [
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014-ref.html": [
+    [
+     {}
+    ]
+   ],
+   "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015-ref.html": [
+    [
+     {}
+    ]
+   ],
    "css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/position-absolute-containing-block-001-ref.html": [
     [
      {}
@@ -269414,6 +269751,16 @@
      {}
     ]
    ],
+   "fetch/corb/README.md": [
+    [
+     {}
+    ]
+   ],
+   "fetch/corb/resources/css-with-json-parser-breaker.css": [
+    [
+     {}
+    ]
+   ],
    "fetch/data-urls/README.md": [
     [
      {}
@@ -271194,6 +271541,11 @@
      {}
     ]
    ],
+   "html/browsers/origin/cross-origin-objects/frame-with-then.html": [
+    [
+     {}
+    ]
+   ],
    "html/browsers/origin/cross-origin-objects/frame.html": [
     [
      {}
@@ -283059,6 +283411,11 @@
      {}
     ]
    ],
+   "media/foo-no-cors.vtt": [
+    [
+     {}
+    ]
+   ],
    "media/foo.vtt": [
     [
      {}
@@ -289669,6 +290026,11 @@
      {}
     ]
    ],
+   "service-workers/service-worker/resources/vtt-frame.html": [
+    [
+     {}
+    ]
+   ],
    "service-workers/service-worker/resources/wait-forever-in-install-worker.js": [
     [
      {}
@@ -291439,6 +291801,11 @@
      {}
     ]
    ],
+   "webaudio/resources/biquad-filters.js": [
+    [
+     {}
+    ]
+   ],
    "webaudio/resources/distance-model-testing.js": [
     [
      {}
@@ -307216,6 +307583,18 @@
      }
     ]
    ],
+   "cookie-store/idlharness.tentative.html": [
+    [
+     "/cookie-store/idlharness.tentative.html",
+     {}
+    ]
+   ],
+   "cookie-store/idlharness_serviceworker.tentative.https.html": [
+    [
+     "/cookie-store/idlharness_serviceworker.tentative.https.html",
+     {}
+    ]
+   ],
    "cookie-store/meta_http_equiv_set_cookie.tentative.html": [
     [
      "/cookie-store/meta_http_equiv_set_cookie.tentative.html",
@@ -308740,6 +309119,12 @@
      {}
     ]
    ],
+   "css/css-fonts/font-variation-settings-serialization-001.html": [
+    [
+     "/css/css-fonts/font-variation-settings-serialization-001.html",
+     {}
+    ]
+   ],
    "css/css-fonts/test_datafont_same_origin.html": [
     [
      "/css/css-fonts/test_datafont_same_origin.html",
@@ -309904,6 +310289,18 @@
      {}
     ]
    ],
+   "css/css-grid/grid-items/grid-minimum-size-grid-items-024.html": [
+    [
+     "/css/css-grid/grid-items/grid-minimum-size-grid-items-024.html",
+     {}
+    ]
+   ],
+   "css/css-grid/grid-items/grid-minimum-size-grid-items-025.html": [
+    [
+     "/css/css-grid/grid-items/grid-minimum-size-grid-items-025.html",
+     {}
+    ]
+   ],
    "css/css-grid/grid-layout-properties.html": [
     [
      "/css/css-grid/grid-layout-properties.html",
@@ -310192,6 +310589,12 @@
      {}
     ]
    ],
+   "css/css-scoping/slotted-link.html": [
+    [
+     "/css/css-scoping/slotted-link.html",
+     {}
+    ]
+   ],
    "css/css-scoping/slotted-parsing.html": [
     [
      "/css/css-scoping/slotted-parsing.html",
@@ -312358,6 +312761,12 @@
      {}
     ]
    ],
+   "css/css-transforms/translate-getComputedStyle.html": [
+    [
+     "/css/css-transforms/translate-getComputedStyle.html",
+     {}
+    ]
+   ],
    "css/css-transitions/before-DOMContentLoaded-001.html": [
     [
      "/css/css-transitions/before-DOMContentLoaded-001.html",
@@ -312742,6 +313151,30 @@
      {}
     ]
    ],
+   "css/css-typed-om/stylevalue-subclasses/cssSkewY.tentative.html": [
+    [
+     "/css/css-typed-om/stylevalue-subclasses/cssSkewY.tentative.html",
+     {}
+    ]
+   ],
+   "css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix-relative-units.html": [
+    [
+     "/css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix-relative-units.html",
+     {}
+    ]
+   ],
+   "css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix.html": [
+    [
+     "/css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix.html",
+     {}
+    ]
+   ],
+   "css/css-typed-om/stylevalue-subclasses/cssTransformValue-toMatrix.html": [
+    [
+     "/css/css-typed-om/stylevalue-subclasses/cssTransformValue-toMatrix.html",
+     {}
+    ]
+   ],
    "css/css-typed-om/stylevalue-subclasses/cssTransformValue.tentative.html": [
     [
      "/css/css-typed-om/stylevalue-subclasses/cssTransformValue.tentative.html",
@@ -314188,6 +314621,12 @@
      {}
     ]
    ],
+   "css/cssom/css-style-attr-decl-block.html": [
+    [
+     "/css/cssom/css-style-attr-decl-block.html",
+     {}
+    ]
+   ],
    "css/cssom/css-style-attribute-modifications.html": [
     [
      "/css/cssom/css-style-attribute-modifications.html",
@@ -314356,6 +314795,12 @@
      {}
     ]
    ],
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    "testharness"
   ],
   "streams/readable-byte-streams/properties.js": [
-   "5eacc7507c71c43bb0f64dc8a7145cd9d3fda167",
+   "9b233802d65e9f3669833641da7953ffd891b423",
    "support"
   ],
   "streams/readable-byte-streams/properties.serviceworker.https.html": [
@@ -592633,6 +593438,10 @@
    "1e7c1c4169bc54bd2046ff5b3392f846c6b7b40f",
    "support"
   ],
+  "webaudio/resources/biquad-filters.js": [
+   "914a0268776de98f3b608babfa5699a93a2cd723",
+   "support"
+  ],
   "webaudio/resources/distance-model-testing.js": [
    "0be27d8bddd91a2c4c6e54d3b52af58bff2ed023",
    "support"
@@ -592817,6 +593626,18 @@
    "bf2de43e568c79b96fd5b0602e26346c483162a5",
    "testharness"
   ],
+  "webaudio/the-audio-api/the-iirfilternode-interface/iirfilter-basic.html": [
+   "176168861bc667b2b05312dbae48f76f7f90d791",
+   "testharness"
+  ],
+  "webaudio/the-audio-api/the-iirfilternode-interface/iirfilter-getFrequencyResponse.html": [
+   "1f1cc3004a65acf09667d3a21150f9ce052f71fb",
+   "testharness"
+  ],
+  "webaudio/the-audio-api/the-iirfilternode-interface/iirfilter.html": [
+   "616e20c9c572762f56a133c1301809dc372157e4",
+   "testharness"
+  ],
   "webaudio/the-audio-api/the-iirfilternode-interface/test-iirfilternode.html": [
    "abe20c222c340c5212297a3b688ef6c9e0f20275",
    "testharness"
@@ -593062,11 +593883,15 @@
    "wdspec"
   ],
   "webdriver/tests/actions/mouse.py": [
-   "708373af0d50f2a0a9776743848482c939f90ec8",
+   "edad7693fcd01b418821942edb870191db64ea41",
    "wdspec"
   ],
   "webdriver/tests/actions/mouse_dblclick.py": [
-   "154d595a3d4466a44c5217c54bb3c717d9a2b9ec",
+   "f6afcb8c0fa017d58a9fcdd3cc474e0c8fd52db5",
+   "wdspec"
+  ],
+  "webdriver/tests/actions/pointer_origin.py": [
+   "a9a99d58daec7719ee53ed758f566ccceb582f65",
    "wdspec"
   ],
   "webdriver/tests/actions/sequence.py": [
@@ -593086,7 +593911,7 @@
    "support"
   ],
   "webdriver/tests/actions/support/mouse.py": [
-   "208a1c4fbc0d5c542d17de7f6474d477ce1feb45",
+   "bc7da107e5b897105dfa7405aa57cba7355854dc",
    "support"
   ],
   "webdriver/tests/actions/support/refine.py": [
@@ -594038,7 +594863,7 @@
    "testharness"
   ],
   "webrtc/RTCPeerConnection-setRemoteDescription-replaceTrack.https.html": [
-   "9a52673bb20dd7eeabd01e6123c90ff181be32ed",
+   "38f2588fadab58203a7f22d25e0d828b1373fbd3",
    "testharness"
   ],
   "webrtc/RTCPeerConnection-setRemoteDescription-rollback.html": [
diff --git a/tests/wpt/metadata/css/css-backgrounds/background-331.html.ini b/tests/wpt/metadata/css/css-backgrounds/background-331.html.ini
index 86f43fb7817..45ff8ab5b26 100644
--- a/tests/wpt/metadata/css/css-backgrounds/background-331.html.ini
+++ b/tests/wpt/metadata/css/css-backgrounds/background-331.html.ini
@@ -3,9 +3,6 @@
   [background_initial_size]
     expected: FAIL
 
-  [background_initial_color]
-    expected: FAIL
-
   [background_initial_position]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/css/css-backgrounds/background-332.html.ini b/tests/wpt/metadata/css/css-backgrounds/background-332.html.ini
index 5078d05643c..5b7808c1541 100644
--- a/tests/wpt/metadata/css/css-backgrounds/background-332.html.ini
+++ b/tests/wpt/metadata/css/css-backgrounds/background-332.html.ini
@@ -12,6 +12,3 @@
   [background_specified_repeat]
     expected: FAIL
 
-  [background_specified_color]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-backgrounds/background-333.html.ini b/tests/wpt/metadata/css/css-backgrounds/background-333.html.ini
index 9a1d17c468e..b8af0d97a00 100644
--- a/tests/wpt/metadata/css/css-backgrounds/background-333.html.ini
+++ b/tests/wpt/metadata/css/css-backgrounds/background-333.html.ini
@@ -3,9 +3,6 @@
   [background_specified_color_size]
     expected: FAIL
 
-  [background_specified_color_color]
-    expected: FAIL
-
   [background_specified_color_position]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/css/css-fonts/font-variation-settings-serialization-001.html.ini b/tests/wpt/metadata/css/css-fonts/font-variation-settings-serialization-001.html.ini
new file mode 100644
index 00000000000..a391657e15e
--- /dev/null
+++ b/tests/wpt/metadata/css/css-fonts/font-variation-settings-serialization-001.html.ini
@@ -0,0 +1,4 @@
+[font-variation-settings-serialization-001.html]
+  [font-feature-settings should be serialized to not include duplicates]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/css-transforms/animation/scale-interpolation.html.ini b/tests/wpt/metadata/css/css-transforms/animation/scale-interpolation.html.ini
index 39e9ec50cb9..0b0c20b9270 100644
--- a/tests/wpt/metadata/css/css-transforms/animation/scale-interpolation.html.ini
+++ b/tests/wpt/metadata/css/css-transforms/animation/scale-interpolation.html.ini
@@ -71,3 +71,21 @@
   [Animation between "none" and "none" at progress 2]
     expected: FAIL
 
+  [Animation between "26 17 9" and "2 1" at progress -1]
+    expected: FAIL
+
+  [Animation between "26 17 9" and "2 1" at progress 0]
+    expected: FAIL
+
+  [Animation between "26 17 9" and "2 1" at progress 0.125]
+    expected: FAIL
+
+  [Animation between "26 17 9" and "2 1" at progress 0.875]
+    expected: FAIL
+
+  [Animation between "26 17 9" and "2 1" at progress 1]
+    expected: FAIL
+
+  [Animation between "26 17 9" and "2 1" at progress 2]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/css-transforms/css-transform-property-existence.html.ini b/tests/wpt/metadata/css/css-transforms/css-transform-property-existence.html.ini
index 7aedd4eb926..542d47ba8df 100644
--- a/tests/wpt/metadata/css/css-transforms/css-transform-property-existence.html.ini
+++ b/tests/wpt/metadata/css/css-transforms/css-transform-property-existence.html.ini
@@ -1,8 +1,5 @@
 [css-transform-property-existence.html]
   type: testharness
-  [Check the existence of transform.]
-    expected: FAIL
-
   [Check the existence of transform-origin.]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/css/css-transforms/parsing/rotate-parsing-valid.html.ini b/tests/wpt/metadata/css/css-transforms/parsing/rotate-parsing-valid.html.ini
new file mode 100644
index 00000000000..789ea6f6fcc
--- /dev/null
+++ b/tests/wpt/metadata/css/css-transforms/parsing/rotate-parsing-valid.html.ini
@@ -0,0 +1,22 @@
+[rotate-parsing-valid.html]
+  [e.style['rotate'\] = "400grad 100 200 300" should set the property value]
+    expected: FAIL
+
+  [e.style['rotate'\] = "x 400grad" should set the property value]
+    expected: FAIL
+
+  [e.style['rotate'\] = "400grad x" should set the property value]
+    expected: FAIL
+
+  [e.style['rotate'\] = "y 400grad" should set the property value]
+    expected: FAIL
+
+  [e.style['rotate'\] = "400grad y" should set the property value]
+    expected: FAIL
+
+  [e.style['rotate'\] = "z 400grad" should set the property value]
+    expected: FAIL
+
+  [e.style['rotate'\] = "400grad z" should set the property value]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/css-transforms/translate-getComputedStyle.html.ini b/tests/wpt/metadata/css/css-transforms/translate-getComputedStyle.html.ini
new file mode 100644
index 00000000000..829073c6d45
--- /dev/null
+++ b/tests/wpt/metadata/css/css-transforms/translate-getComputedStyle.html.ini
@@ -0,0 +1,4 @@
+[translate-getComputedStyle.html]
+  [computed style for translate]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/cssom-view/elementsFromPoint-iframes.html.ini b/tests/wpt/metadata/css/cssom-view/elementsFromPoint-iframes.html.ini
index 171592fc08f..6ef8bb1049f 100644
--- a/tests/wpt/metadata/css/cssom-view/elementsFromPoint-iframes.html.ini
+++ b/tests/wpt/metadata/css/cssom-view/elementsFromPoint-iframes.html.ini
@@ -2,3 +2,6 @@
   [elementsFromPoint on the root document for points in iframe elements]
     expected: FAIL
 
+  [elementsFromPoint on inner documents]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/cssom/css-style-attr-decl-block.html.ini b/tests/wpt/metadata/css/cssom/css-style-attr-decl-block.html.ini
new file mode 100644
index 00000000000..1b75a4d001c
--- /dev/null
+++ b/tests/wpt/metadata/css/cssom/css-style-attr-decl-block.html.ini
@@ -0,0 +1,7 @@
+[css-style-attr-decl-block.html]
+  [Changes to CSS declaration block should queue mutation record for style attribute]
+    expected: FAIL
+
+  [Removing non-existing property or setting invalid value on CSS declaration block shouldn't queue mutation record]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/cssom/cssimportrule.html.ini b/tests/wpt/metadata/css/cssom/cssimportrule.html.ini
index 8413360623f..eb8fb0ec633 100644
--- a/tests/wpt/metadata/css/cssom/cssimportrule.html.ini
+++ b/tests/wpt/metadata/css/cssom/cssimportrule.html.ini
@@ -15,3 +15,12 @@
   [MediaList mediaText attribute should be updated]
     expected: FAIL
 
+  [CSSImportRule : MediaList mediaText attribute should be updated due to [PutForwards\]]
+    expected: FAIL
+
+  [CSSStyleDeclaration cssText attribute should be updated due to [PutForwards\]]
+    expected: FAIL
+
+  [StyleSheet : MediaList mediaText attribute should be updated due to [PutForwards\]]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/cssom/selectorText-modification-restyle-002.html.ini b/tests/wpt/metadata/css/cssom/selectorText-modification-restyle-002.html.ini
new file mode 100644
index 00000000000..d9572003e6e
--- /dev/null
+++ b/tests/wpt/metadata/css/cssom/selectorText-modification-restyle-002.html.ini
@@ -0,0 +1,4 @@
+[selectorText-modification-restyle-002.html]
+  [CSSOM: Modify selectorText in a shadow tree stylesheet]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/custom-elements/Document-createElement.html.ini b/tests/wpt/metadata/custom-elements/Document-createElement.html.ini
index b3c0d410753..d4651069a7a 100644
--- a/tests/wpt/metadata/custom-elements/Document-createElement.html.ini
+++ b/tests/wpt/metadata/custom-elements/Document-createElement.html.ini
@@ -2,3 +2,6 @@
   [document.createElement with unknown "is" value should create "undefined" state element]
     expected: FAIL
 
+  [document.createElement must create an instance of autonomous custom elements when it has is attribute]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/custom-elements/upgrading/Document-importNode.html.ini b/tests/wpt/metadata/custom-elements/upgrading/Document-importNode.html.ini
new file mode 100644
index 00000000000..b5449201d15
--- /dev/null
+++ b/tests/wpt/metadata/custom-elements/upgrading/Document-importNode.html.ini
@@ -0,0 +1,4 @@
+[Document-importNode.html]
+  [built-in: document.importNode() should import "undefined" custom elements successfully]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/custom-elements/upgrading/Node-cloneNode.html.ini b/tests/wpt/metadata/custom-elements/upgrading/Node-cloneNode.html.ini
new file mode 100644
index 00000000000..47aab04dca8
--- /dev/null
+++ b/tests/wpt/metadata/custom-elements/upgrading/Node-cloneNode.html.ini
@@ -0,0 +1,4 @@
+[Node-cloneNode.html]
+  [Node.prototype.cloneNode(false) must be able to clone as a customized built-in element when it has an inconsistent "is" attribute]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/domparsing/XMLSerializer-serializeToString.html.ini b/tests/wpt/metadata/domparsing/XMLSerializer-serializeToString.html.ini
index c11898eb2f0..96c22d76135 100644
--- a/tests/wpt/metadata/domparsing/XMLSerializer-serializeToString.html.ini
+++ b/tests/wpt/metadata/domparsing/XMLSerializer-serializeToString.html.ini
@@ -12,3 +12,6 @@
   [Check if there is no redundant empty namespace declaration.]
     expected: FAIL
 
+  [check XMLSerializer.serializeToString escapes attribute values for roundtripping]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/html/dom/documents/dom-tree-accessors/Document.body.html.ini b/tests/wpt/metadata/html/dom/documents/dom-tree-accessors/Document.body.html.ini
new file mode 100644
index 00000000000..b19ab8eb8ce
--- /dev/null
+++ b/tests/wpt/metadata/html/dom/documents/dom-tree-accessors/Document.body.html.ini
@@ -0,0 +1,4 @@
+[Document.body.html]
+  [Setting document.body to a new body element when the root element is a test element.]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/html/infrastructure/common-dom-interfaces/collections/historical.html.ini b/tests/wpt/metadata/html/infrastructure/common-dom-interfaces/collections/historical.html.ini
new file mode 100644
index 00000000000..8383b76c36c
--- /dev/null
+++ b/tests/wpt/metadata/html/infrastructure/common-dom-interfaces/collections/historical.html.ini
@@ -0,0 +1,4 @@
+[historical.html]
+  [HTMLAllCollection legacycaller with two arguments should not be supported]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/html/obsolete/requirements-for-implementations/other-elements-attributes-and-apis/document-color-01.html.ini b/tests/wpt/metadata/html/obsolete/requirements-for-implementations/other-elements-attributes-and-apis/document-color-01.html.ini
index 60423ede964..44c5a52b26a 100644
--- a/tests/wpt/metadata/html/obsolete/requirements-for-implementations/other-elements-attributes-and-apis/document-color-01.html.ini
+++ b/tests/wpt/metadata/html/obsolete/requirements-for-implementations/other-elements-attributes-and-apis/document-color-01.html.ini
@@ -9,3 +9,15 @@
   [setting document color attributes with no body]
     expected: FAIL
 
+  [document color attributes when the root element is a test element (iframe)]
+    expected: FAIL
+
+  [document color attributes when the root element is a test element (createHTMLDocument)]
+    expected: FAIL
+
+  [getting document color attributes when document.body is a frameset]
+    expected: FAIL
+
+  [setting document color attributes when document.body is a frameset]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/innerText/getter.html.ini b/tests/wpt/metadata/innerText/getter.html.ini
index 97483adcfd1..74d27c7720d 100644
--- a/tests/wpt/metadata/innerText/getter.html.ini
+++ b/tests/wpt/metadata/innerText/getter.html.ini
@@ -239,3 +239,6 @@
   [<video> contents ignored ("<div><video>abc")]
     expected: FAIL
 
+  [innerText getter test]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/xhr/xmlhttprequest-sync-default-feature-policy.sub.html.ini b/tests/wpt/metadata/xhr/xmlhttprequest-sync-default-feature-policy.sub.html.ini
index 52e7f0fcea5..b1e3d945142 100644
--- a/tests/wpt/metadata/xhr/xmlhttprequest-sync-default-feature-policy.sub.html.ini
+++ b/tests/wpt/metadata/xhr/xmlhttprequest-sync-default-feature-policy.sub.html.ini
@@ -1,5 +1,5 @@
 [xmlhttprequest-sync-default-feature-policy.sub.html]
-  expected: TIMEOUT
+  expected: ERROR
   [Default "sync-xhr" feature policy ["*"\] allows same-origin iframes.]
     expected: TIMEOUT
 
diff --git a/tests/wpt/web-platform-tests/README.md b/tests/wpt/web-platform-tests/README.md
index 0247e8c69ce..90f1f47aa4e 100644
--- a/tests/wpt/web-platform-tests/README.md
+++ b/tests/wpt/web-platform-tests/README.md
@@ -32,17 +32,22 @@ your `%Path%` [Environment Variable](http://www.computerhope.com/issues/ch000549
 and read the [Windows Notes](#windows-notes) section below.
 
 To get the tests running, you need to set up the test domains in your
-[`hosts` file](http://en.wikipedia.org/wiki/Hosts_%28file%29%23Location_in_the_file_system). The
-following entries are required:
+[`hosts` file](http://en.wikipedia.org/wiki/Hosts_%28file%29%23Location_in_the_file_system).
 
+The necessary content can be generated with `./wpt make-hosts-file`; on
+Windows, you will need to preceed the prior command with `python` or
+the path to the Python binary (`python wpt make-hosts-file`).
+
+For example, on most UNIX-like systems, you can setup the hosts file with:
+
+```bash
+./wpt make-hosts-file | sudo tee -a /etc/hosts
 ```
-127.0.0.1   web-platform.test
-127.0.0.1   www.web-platform.test
-127.0.0.1   www1.web-platform.test
-127.0.0.1   www2.web-platform.test
-127.0.0.1   xn--n8j6ds53lwwkrqhv28a.web-platform.test
-127.0.0.1   xn--lve-6lad.web-platform.test
-0.0.0.0     nonexistent-origin.web-platform.test
+
+And on Windows (note this requires an Administrator privileged shell):
+
+```bash
+python wpt make-hosts-file >> %SystemRoot%\System32\drivers\etc\hosts
 ```
 
 If you are behind a proxy, you also need to make sure the domains above are
diff --git a/tests/wpt/web-platform-tests/console/console-format-specifier-symbol-manual.html b/tests/wpt/web-platform-tests/console/console-format-specifier-symbol-manual.html
new file mode 100644
index 00000000000..47a981fba69
--- /dev/null
+++ b/tests/wpt/web-platform-tests/console/console-format-specifier-symbol-manual.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title>Console Format Specifiers on Symbols</title>
+<meta name="author" title="Dominic Farolino" href="mailto:domfarolino@gmail.com">
+<meta name="assert" content="Console format specifiers on Symbols">
+<link rel="help" href="https://console.spec.whatwg.org/#formatter">
+</head>
+<body>
+<p>Open the console inside the developer tools. It should contain five lines, each of which are:</p>
+<p><code>Symbol(description)</code></p>
+
+<script>
+console.log("%s", Symbol.for("description"));
+console.dirxml("%s", Symbol.for("description"));
+console.trace("%s", Symbol.for("description"));
+console.group("%s", Symbol.for("description"));
+console.groupCollapsed("%s", Symbol.for("description"));
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/cookie-store/cookie-store.idl b/tests/wpt/web-platform-tests/cookie-store/cookie-store.idl
new file mode 100644
index 00000000000..d4f64593741
--- /dev/null
+++ b/tests/wpt/web-platform-tests/cookie-store/cookie-store.idl
@@ -0,0 +1,56 @@
+// https://github.com/WICG/cookie-store/blob/gh-pages/explainer.md
+
+dictionary CookieListItem {
+  USVString name;
+  USVString value;
+};
+
+typedef sequence<CookieListItem> CookieList;
+
+[
+  Exposed=(ServiceWorker,Window)
+] interface CookieStore {
+  Promise<CookieList?> getAll(USVString name, optional CookieStoreGetOptions options);
+  Promise<CookieList?> getAll(optional CookieStoreGetOptions options);
+
+  Promise<CookieListItem?> get(USVString name, optional CookieStoreGetOptions options);
+  Promise<CookieListItem?> get(optional CookieStoreGetOptions options);
+
+  Promise<boolean> has(USVString name, optional CookieStoreGetOptions options);
+  Promise<boolean> has(optional CookieStoreGetOptions options);
+
+  Promise<void> set(USVString name, USVString value, optional CookieStoreSetOptions options);
+  Promise<void> set(CookieStoreSetOptions options);
+
+  Promise<void> delete(USVString name, optional CookieStoreSetOptions options);
+  Promise<void> delete(CookieStoreSetOptions options);
+};
+
+enum CookieMatchType {
+  "equals",
+  "startsWith"
+};
+
+dictionary CookieStoreGetOptions {
+  USVString name;
+  USVString url;
+  CookieMatchType matchType = "equals";
+};
+
+dictionary CookieStoreSetOptions {
+  USVString name;
+  USVString value;
+  DOMTimeStamp? expires = null;
+  USVString domain;
+  USVString path = "/";
+  boolean? secure;
+  boolean httpOnly = false;
+};
+
+partial interface Window {
+  [Replaceable, SameObject] readonly attribute CookieStore cookieStore;
+};
+
+partial interface ServiceWorkerGlobalScope {
+  [Replaceable, SameObject] readonly attribute CookieStore cookieStore;
+};
diff --git a/tests/wpt/web-platform-tests/cookie-store/idlharness.tentative.html b/tests/wpt/web-platform-tests/cookie-store/idlharness.tentative.html
new file mode 100644
index 00000000000..cf80246409e
--- /dev/null
+++ b/tests/wpt/web-platform-tests/cookie-store/idlharness.tentative.html
@@ -0,0 +1,35 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>Async Cookies: IDL tests</title>
+<link rel="help" href="https://github.com/WICG/cookie-store"/>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script>
+'use strict';
+
+promise_test(async t => {
+  const urls = ['/interfaces/html.idl', 'cookie-store.idl'];
+  const [html, cookie_store] = await Promise.all(
+    urls.map(url => fetch(url).then(response => response.text())));
+
+  const idl_array = new IdlArray();
+
+  // Dependencies of HTML
+  idl_array.add_untested_idls('interface Document {};');
+  idl_array.add_untested_idls('interface LinkStyle {};');
+  idl_array.add_untested_idls(html);
+
+  idl_array.add_untested_idls(
+    `[Global=ServiceWorker, Exposed=ServiceWorker]
+     interface ServiceWorkerGlobalScope {};`);
+
+  idl_array.add_idls(cookie_store);
+
+  idl_array.add_objects({
+    CookieStore: [self.cookieStore],
+  });
+  idl_array.test();
+}, 'Interface test');
+</script>
diff --git a/tests/wpt/web-platform-tests/cookie-store/idlharness_serviceworker.js b/tests/wpt/web-platform-tests/cookie-store/idlharness_serviceworker.js
new file mode 100644
index 00000000000..35eccfd41da
--- /dev/null
+++ b/tests/wpt/web-platform-tests/cookie-store/idlharness_serviceworker.js
@@ -0,0 +1,31 @@
+self.GLOBAL = {
+  isWindow: function() { return false; },
+  isWorker: function() { return true; },
+};
+importScripts('/resources/testharness.js',
+              '/resources/WebIDLParser.js',
+              '/resources/idlharness.js');
+
+promise_test(async t => {
+  const urls = ['cookie-store.idl'];
+  const [cookie_store] = await Promise.all(
+    urls.map(url => fetch(url).then(response => response.text())));
+
+  const idl_array = new IdlArray();
+
+  idl_array.add_untested_idls(
+    `[Global=ServiceWorker, Exposed=ServiceWorker]
+     interface ServiceWorkerGlobalScope {};`);
+  idl_array.add_untested_idls(
+    `[Global=Window, Exposed=Window]
+     interface Window {};`);
+
+  idl_array.add_idls(cookie_store);
+
+  idl_array.add_objects({
+    CookieStore: [self.cookieStore],
+  });
+  idl_array.test();
+}, 'Interface test');
+
+done();
diff --git a/tests/wpt/web-platform-tests/cookie-store/idlharness_serviceworker.tentative.https.html b/tests/wpt/web-platform-tests/cookie-store/idlharness_serviceworker.tentative.https.html
new file mode 100644
index 00000000000..845a9fdd7e0
--- /dev/null
+++ b/tests/wpt/web-platform-tests/cookie-store/idlharness_serviceworker.tentative.https.html
@@ -0,0 +1,21 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>Async Cookies: ServiceWorker IDL tests</title>
+<link rel="help" href="https://github.com/WICG/cookie-store">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+'use strict';
+
+(async () => {
+  const scope = 'does/not/exist';
+
+  let registration = await navigator.serviceWorker.getRegistration(scope);
+  if (registration)
+    await registration.unregister();
+  registration = await navigator.serviceWorker.register(
+      'idlharness_serviceworker.js', {scope});
+
+  fetch_tests_from_worker(registration.installing);
+})();
+</script>
diff --git a/tests/wpt/web-platform-tests/css/CSS2/floats/intrinsic-size-float-and-line.html b/tests/wpt/web-platform-tests/css/CSS2/floats/intrinsic-size-float-and-line.html
new file mode 100644
index 00000000000..06031245491
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/CSS2/floats/intrinsic-size-float-and-line.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<title>Put float next to line in shrink-to-fit container</title>
+<link rel="author" title="Morten Stenshorne" href="mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/CSS22/visudet.html#float-width" title="10.3.5 Floating, non-replaced elements">
+<link rel="match" href="../../reference/ref-filled-green-200px-square.html">
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="float:left; min-width:150px; background:red;">
+  <div style="float:right; width:100px; height:200px; background:green;"></div>
+  <div style="vertical-align:top; display:inline-block; width:100px; height:200px; background:green;"></div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/CSS2/visudet/reference/content-height-005-ref.html b/tests/wpt/web-platform-tests/css/CSS2/visudet/reference/content-height-005-ref.html
index 70a3ee07840..b68f8a94196 100644
--- a/tests/wpt/web-platform-tests/css/CSS2/visudet/reference/content-height-005-ref.html
+++ b/tests/wpt/web-platform-tests/css/CSS2/visudet/reference/content-height-005-ref.html
@@ -2,6 +2,7 @@
 <meta charset="utf-8">
 <title>CSS Test Reference file</title>
 <link rel="author" title="Florian Rivoal" href="https://florian.rivoal.net">
+<style>
 
 div {
   font-size: 50px;
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/background-331.html b/tests/wpt/web-platform-tests/css/css-backgrounds/background-331.html
index 3d72ad408dd..121623453a6 100644
--- a/tests/wpt/web-platform-tests/css/css-backgrounds/background-331.html
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/background-331.html
@@ -57,7 +57,7 @@
 
         test(function() {
             assert_equals(cs.getPropertyValue("background-color"),
-                "transparent", "background initial value for background-color");
+                "rgba(0, 0, 0, 0)", "background initial value for background-color");
         }, "background_initial_color");
     </script>
   </body>
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/background-332.html b/tests/wpt/web-platform-tests/css/css-backgrounds/background-332.html
index da11dc8cd58..2621cb669b7 100644
--- a/tests/wpt/web-platform-tests/css/css-backgrounds/background-332.html
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/background-332.html
@@ -57,7 +57,7 @@
 
         test(function() {
             assert_equals(cs.getPropertyValue("background-color"),
-                "gray", "background specified value for background-color");
+                "rgb(128, 128, 128)", "background specified value for background-color");
         }, "background_specified_color");
     </script>
   </body>
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/background-333.html b/tests/wpt/web-platform-tests/css/css-backgrounds/background-333.html
index 8331527dbbc..53dd15053c4 100644
--- a/tests/wpt/web-platform-tests/css/css-backgrounds/background-333.html
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/background-333.html
@@ -57,7 +57,7 @@
 
         test(function() {
             assert_equals(cs.getPropertyValue("background-color"),
-                "red", "background specified value for background-color");
+                "rgb(255, 0, 0)", "background specified value for background-color");
         }, "background_specified_color_color");
     </script>
   </body>
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/box-shadow-syntax-001.xht b/tests/wpt/web-platform-tests/css/css-backgrounds/box-shadow-syntax-001.xht
index 4e32c9fe168..4df5907080d 100644
--- a/tests/wpt/web-platform-tests/css/css-backgrounds/box-shadow-syntax-001.xht
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/box-shadow-syntax-001.xht
@@ -21,7 +21,7 @@
     }
     .inset {
       color: green;
-      height: 13px;
+      height: 12px;
       margin: -1px 0 -4px -4px;
     }
 
diff --git a/tests/wpt/web-platform-tests/css/css-backgrounds/reference/box-shadow-syntax-001.xht b/tests/wpt/web-platform-tests/css/css-backgrounds/reference/box-shadow-syntax-001.xht
index 697c21a9824..34be7bc52f1 100644
--- a/tests/wpt/web-platform-tests/css/css-backgrounds/reference/box-shadow-syntax-001.xht
+++ b/tests/wpt/web-platform-tests/css/css-backgrounds/reference/box-shadow-syntax-001.xht
@@ -10,6 +10,7 @@
       border: solid green 4px;
       padding-top: 1px;
       border-style: none none solid solid;
+      height: 7px;
     }
   </style>
  </head>
diff --git a/tests/wpt/web-platform-tests/css/css-fonts/font-variation-settings-serialization-001.html b/tests/wpt/web-platform-tests/css/css-fonts/font-variation-settings-serialization-001.html
new file mode 100644
index 00000000000..65178c978d3
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-fonts/font-variation-settings-serialization-001.html
@@ -0,0 +1,24 @@
+<!doctype html>
+<html>
+    <head>
+        <meta charset="utf-8">
+        <title>CSS Test: font-feature-settings serialization</title>
+        <link rel="author" title="Greg Whitworth" href="mailto:gwhit@microsoft.com">
+        <link rel="help" href="http://www.w3.org/TR/css-fonts-4/#propdef-font-variation-settings">
+        <link rel="issue" href="https://github.com/w3c/csswg-drafts/issues/1959#issuecomment-360864254">
+        <meta name="desctiption" content="It was decided in issue 1959 that font-variation-settings is a map, therefor duplicates should be removed">
+        <script src="/resources/testharness.js"></script>
+        <script src="/resources/testharnessreport.js"></script>
+    </head>
+    <body>
+        <div id="test1" style='font-variation-settings: "bldA" 1, "bldA" 2'></div>
+
+        <script>
+            const test1_canEqual = ['"bldA" 2', "'bldA' 2"];
+            test(function() {
+                assert_in_array(getComputedStyle(document.getElementById('test1')).fontVariationSettings, test1_canEqual);
+            }, "font-feature-settings should be serialized to not include duplicates");
+        </script>
+    </body>
+</html>
+
diff --git a/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-022.html b/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-022.html
index 66417a4cd78..127ea8df4af 100644
--- a/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-022.html
+++ b/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-022.html
@@ -135,3 +135,217 @@
   <div data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
   <div data-expected-width="25"></div>
 </div>
+
+<h3>grid content writing-mode: vertical-lr;</h3>
+
+<pre>grid-template-columns: auto;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: auto;">
+  <div data-expected-height="100">XXXXXXXXXX</div>
+  <div data-expected-height="100"></div>
+</div>
+
+<pre>grid-template-columns: 0px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: 0px;">
+  <div data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-columns: 25px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: 25px;">
+  <div data-expected-height="25">XXXXXXXXXX</div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px);</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px);</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="25">XXXXXXXXXX</div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item margin height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="0" style="margin: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item margin height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="15" style="margin: 5px 0px;"></div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item padding height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="10" style="padding: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item padding height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="25" style="padding: 5px 0px;"></div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item border height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="10" style="border: solid 5px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item border height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="25" style="border: solid 5px blue;"></div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="25"></div>
+</div>
+
+<h3>grid content writing-mode: vertical-rl;</h3>
+
+<pre>grid-template-columns: auto;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: auto;">
+  <div data-expected-height="100">XXXXXXXXXX</div>
+  <div data-expected-height="100"></div>
+</div>
+
+<pre>grid-template-columns: 0px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: 0px;">
+  <div data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-columns: 25px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: 25px;">
+  <div data-expected-height="25">XXXXXXXXXX</div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px);</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px);</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="25">XXXXXXXXXX</div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item margin height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="0" style="margin: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item margin height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="15" style="margin: 5px 0px;"></div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item padding height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="10" style="padding: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item padding height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="25" style="padding: 5px 0px;"></div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item border height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="10" style="border: solid 5px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item border height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="25" style="border: solid 5px blue;"></div>
+  <div data-expected-height="25"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px);">
+  <div data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 25px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 25px);">
+  <div data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="25"></div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-023.html b/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-023.html
index d821e5c735c..636a40fcb2d 100644
--- a/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-023.html
+++ b/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-023.html
@@ -32,7 +32,7 @@
 
 <div id="log"></div>
 
-<h3>writing-mode: vertical-lr;</h3>
+<h3>item writing-mode: vertical-lr;</h3>
 
 <pre>grid-template-rows: auto;</pre>
 
@@ -139,7 +139,7 @@
   <div data-expected-height="25"></div>
 </div>
 
-<h3>writing-mode: vertical-rl;</h3>
+<h3>item writing-mode: vertical-rl;</h3>
 
 <pre>grid-template-rows: auto;</pre>
 
@@ -246,3 +246,216 @@
   <div data-expected-height="25"></div>
 </div>
 
+<h3>grid container writing-mode: vertical-lr; &amp; item writing-mode: horizontal-tb;</h3>
+
+<pre>grid-template-rows: auto;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: auto;">
+  <div class="horizontalTB" data-expected-width="100">XXXXXXXXXX</div>
+  <div data-expected-width="100"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px);</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-rows: 25px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: 25px;">
+  <div class="horizontalTB" data-expected-width="25">XXXXXXXXXX</div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px);</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px);</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="25">XXXXXXXXXX</div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item margin width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0" style="margin: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item margin width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="15" style="margin: 0px 5px;"></div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item padding width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="padding: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item padding width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="25" style="padding: 0px 5px;"></div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item border width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="border: solid 5px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item border width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="25" style="border: solid 5px blue;"></div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="25"></div>
+</div>
+
+<h3>grid container writing-mode: vertical-rl; &amp; item writing-mode: horizontal-tb;</h3>
+
+<pre>grid-template-rows: auto;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: auto;">
+  <div class="horizontalTB" data-expected-width="100">XXXXXXXXXX</div>
+  <div data-expected-width="100"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px);</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-rows: 25px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: 25px;">
+  <div class="horizontalTB" data-expected-width="25">XXXXXXXXXX</div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px);</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px);</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="25">XXXXXXXXXX</div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item margin width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0" style="margin: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item margin width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="15" style="margin: 0px 5px;"></div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item padding width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="padding: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item padding width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="25" style="padding: 0px 5px;"></div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item border width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="border: solid 5px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item border width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="25" style="border: solid 5px blue;"></div>
+  <div data-expected-width="25"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 25px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 25px);">
+  <div class="horizontalTB" data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="25"></div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-024.html b/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-024.html
new file mode 100644
index 00000000000..fb706bfca59
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-024.html
@@ -0,0 +1,355 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Grid Layout Test: Minimum size of grid items</title>
+<link rel="author" title="Manuel Rego Casasnovas" href="mailto:rego@igalia.com">
+<link rel="help" href="http://www.w3.org/TR/css-grid-1/#min-size-auto" title="6.5. Implied Minimum Size of Grid Items">
+<meta name="assert" content="Checks that automatic minimum size is clamped with different column sizes and spaning items.">
+<link rel="stylesheet" href="../support/grid.css">
+<style>
+.grid {
+  border: solid thick;
+  font: 10px/1 Ahem;
+  width: 50px;
+  height: 50px;
+  grid-template-rows: 25px 25px;
+}
+
+.grid > div {
+  grid-column: span 2;
+}
+
+.grid > div:nth-child(1) {
+  color: blue;
+  background: cyan;
+}
+
+.grid > div:nth-child(2) {
+  background: magenta;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.grid')">
+
+<div id="log"></div>
+
+<pre>grid-template-columns: auto auto;</pre>
+
+<div class="grid" style="grid-template-columns: auto auto;">
+  <div data-expected-width="100">XXXXXXXXXX</div>
+  <div data-expected-width="100"></div>
+</div>
+
+<pre>grid-template-columns: 0px 0px;</pre>
+
+<div class="grid" style="grid-template-columns: 0px 0px;">
+  <div data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-columns: 20px 20px;</pre>
+
+<div class="grid" style="grid-template-columns: 20px 20px;">
+  <div data-expected-width="40">XXXXXXXXXX</div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-width="40">XXXXXXXXXX</div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item width: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item width: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item margin width: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-width="0" style="margin: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item margin width: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-width="30" style="margin: 0px 5px;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item padding width: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-width="10" style="padding: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item padding width: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-width="40" style="padding: 0px 5px;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item border width: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-width="10" style="border: solid 5px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item border width: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-width="40" style="border: solid 5px blue;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<h3>grid content writing-mode: vertical-lr;</h3>
+
+<pre>grid-template-columns: auto auto;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: auto auto;">
+  <div data-expected-height="100">XXXXXXXXXX</div>
+  <div data-expected-height="100"></div>
+</div>
+
+<pre>grid-template-columns: 0px 0px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: 0px 0px;">
+  <div data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-columns: 20px 20px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: 20px 20px;">
+  <div data-expected-height="40">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="40">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item margin height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="0" style="margin: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item margin height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="30" style="margin: 5px 0px;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item padding height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="10" style="padding: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item padding height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="40" style="padding: 5px 0px;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item border height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="10" style="border: solid 5px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item border height: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="40" style="border: solid 5px blue;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<h3>grid content writing-mode: vertical-rl;</h3>
+
+<pre>grid-template-columns: auto auto;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: auto auto;">
+  <div data-expected-height="100">XXXXXXXXXX</div>
+  <div data-expected-height="100"></div>
+</div>
+
+<pre>grid-template-columns: 0px 0px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: 0px 0px;">
+  <div data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-columns: 20px 20px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: 20px 20px;">
+  <div data-expected-height="40">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="40">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item margin height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="0" style="margin: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item margin height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="30" style="margin: 5px 0px;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item padding height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="10" style="padding: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item padding height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="40" style="padding: 5px 0px;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item border height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="10" style="border: solid 5px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item border height: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="40" style="border: solid 5px blue;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 0px) minmax(auto, 0px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 0px) minmax(auto, 0px);">
+  <div data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-columns: minmax(auto, 20px) minmax(auto, 20px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-columns: minmax(auto, 20px) minmax(auto, 20px);">
+  <div data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="40"></div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-025.html b/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-025.html
new file mode 100644
index 00000000000..722426e0c9b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-grid/grid-items/grid-minimum-size-grid-items-025.html
@@ -0,0 +1,465 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Grid Layout Test: Minimum size of grid items</title>
+<link rel="author" title="Manuel Rego Casasnovas" href="mailto:rego@igalia.com">
+<link rel="help" href="http://www.w3.org/TR/css-grid-1/#min-size-auto" title="6.5. Implied Minimum Size of Grid Items">
+<meta name="assert" content="Checks that automatic minimum size is clamped with different row sizes and spaning items.">
+<link rel="stylesheet" href="../support/grid.css">
+<style>
+.grid {
+  border: solid thick;
+  font: 10px/1 Ahem;
+  width: 50px;
+  height: 50px;
+  grid-template-columns: 25px 25px;
+  margin: 50px 0px;
+}
+
+.grid > div {
+  grid-row: span 2;
+}
+
+.grid > div:nth-child(1) {
+  color: blue;
+  background: cyan;
+}
+
+.grid > div:nth-child(2) {
+  background: magenta;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.grid')">
+
+<div id="log"></div>
+
+<h3>item writing-mode: vertical-lr;</h3>
+
+<pre>grid-template-rows: auto auto;</pre>
+
+<div class="grid" style="grid-template-rows: auto auto;">
+  <div class="verticalLR" data-expected-height="100">XXXXXXXXXX</div>
+  <div data-expected-height="100"></div>
+</div>
+
+<pre>grid-template-rows: 0px 0px;</pre>
+
+<div class="grid" style="grid-template-rows: 0px 0px;">
+  <div class="verticalLR" data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-rows: 20px 20px;</pre>
+
+<div class="grid" style="grid-template-rows: 20px 20px;">
+  <div class="verticalLR" data-expected-height="40">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalLR" data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalLR" data-expected-height="40">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalLR" data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalLR" data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item margin height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalLR" data-expected-height="0" style="margin: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item margin height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalLR" data-expected-height="30" style="margin: 5px 0px;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item padding height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalLR" data-expected-height="10" style="padding: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item padding height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalLR" data-expected-height="40" style="padding: 5px 0px;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item border height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalLR" data-expected-height="10" style="border: solid 5px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item border height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalLR" data-expected-height="40" style="border: solid 5px blue;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalLR" data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalLR" data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<h3>item writing-mode: vertical-rl;</h3>
+
+<pre>grid-template-rows: auto auto;</pre>
+
+<div class="grid" style="grid-template-rows: auto auto;">
+  <div class="verticalRL" data-expected-height="100">XXXXXXXXXX</div>
+  <div data-expected-height="100"></div>
+</div>
+
+<pre>grid-template-rows: 0px 0px;</pre>
+
+<div class="grid" style="grid-template-rows: 0px 0px;">
+  <div class="verticalRL" data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-rows: 20px 20px;</pre>
+
+<div class="grid" style="grid-template-rows: 20px 20px;">
+  <div class="verticalRL" data-expected-height="40">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalRL" data-expected-height="0">XXXXXXXXXX</div>
+  <div data-expected-height="0"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalRL" data-expected-height="40">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalRL" data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalRL" data-expected-height="10" style="height: 10px;">XXXXXXXXXX</div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item margin height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalRL" data-expected-height="0" style="margin: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item margin height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalRL" data-expected-height="30" style="margin: 5px 0px;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item padding height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalRL" data-expected-height="10" style="padding: 5px 0px;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item padding height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalRL" data-expected-height="40" style="padding: 5px 0px;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item border height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalRL" data-expected-height="10" style="border: solid 5px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item border height: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalRL" data-expected-height="40" style="border: solid 5px blue;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="verticalRL" data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item height + margin + border + padding: 10px;</pre>
+
+<div class="grid" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="verticalRL" data-expected-height="8" style="height: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-height="40"></div>
+</div>
+
+<h3>grid container writing-mode: vertical-lr; &amp; item writing-mode: horizontal-tb;</h3>
+
+<pre>grid-template-rows: auto auto;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: auto auto;">
+  <div class="horizontalTB" data-expected-width="100">XXXXXXXXXX</div>
+  <div data-expected-width="100"></div>
+</div>
+
+<pre>grid-template-rows: 0px 0px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: 0px 0px;">
+  <div class="horizontalTB" data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-rows: 20px 20px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: 20px 20px;">
+  <div class="horizontalTB" data-expected-width="40">XXXXXXXXXX</div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="40">XXXXXXXXXX</div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item margin width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0" style="margin: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item margin width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="30" style="margin: 0px 5px;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item padding width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="padding: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item padding width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="40" style="padding: 0px 5px;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item border width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="border: solid 5px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item border width: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="40" style="border: solid 5px blue;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalLR" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<h3>grid container writing-mode: vertical-rl; &amp; item writing-mode: horizontal-tb;</h3>
+
+<pre>grid-template-rows: auto auto;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: auto auto;">
+  <div class="horizontalTB" data-expected-width="100">XXXXXXXXXX</div>
+  <div data-expected-width="100"></div>
+</div>
+
+<pre>grid-template-rows: 0px 0px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: 0px 0px;">
+  <div class="horizontalTB" data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-rows: 20px 20px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: 20px 20px;">
+  <div class="horizontalTB" data-expected-width="40">XXXXXXXXXX</div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0">XXXXXXXXXX</div>
+  <div data-expected-width="0"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="40">XXXXXXXXXX</div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="10" style="width: 10px;">XXXXXXXXXX</div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item margin width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="0" style="margin: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item margin width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="30" style="margin: 0px 5px;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item padding width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="padding: 0px 5px;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item padding width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="40" style="padding: 0px 5px;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item border width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="10" style="border: solid 5px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item border width: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="40" style="border: solid 5px blue;"></div>
+  <div data-expected-width="40"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 0px) minmax(auto, 0px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 0px) minmax(auto, 0px);">
+  <div class="horizontalTB" data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="10"></div>
+</div>
+
+<pre>grid-template-rows: minmax(auto, 20px) minmax(auto, 20px); item width + margin + border + padding: 10px;</pre>
+
+<div class="grid verticalRL" style="grid-template-rows: minmax(auto, 20px) minmax(auto, 20px);">
+  <div class="horizontalTB" data-expected-width="8" style="width: 4px; margin: 1px; padding: 1px; border: solid 1px blue;"></div>
+  <div data-expected-width="40"></div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-registered-ref.html b/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-registered-ref.html
new file mode 100644
index 00000000000..0ba98620157
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-registered-ref.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<style>
+.container {
+  margin: 20px 0;
+  border: solid 2px;
+  width: 100px;
+}
+
+.pink {
+  background: hotpink;
+}
+</style>
+
+<div class="container">
+  <div class="pink" style="width: 50px; height: 100px;"></div>
+</div>
+
+<div class="container">
+  <div class="pink" style="width: 100px; height: 100px;"></div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-registered.https.html b/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-registered.https.html
new file mode 100644
index 00000000000..eb3fb678da2
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-registered.https.html
@@ -0,0 +1,66 @@
+<!DOCTYPE html>
+<html class=reftest-wait>
+<link rel="help" href="https://drafts.css-houdini.org/css-layout-api/#layout-api-box-tree">
+<link rel="match" href="box-tree-registered-ref.html">
+<meta name="assert" content="This test checks that a registered layout() has children which are blockified and new formatting contexts." />
+<style>
+@supports (display: layout(registered)) {
+  .test {
+    display: layout(registered);
+  }
+}
+
+.container {
+  margin: 20px 0;
+  border: solid 2px;
+  width: 100px;
+}
+
+.float {
+  float: left;
+  width: 50%;
+  height: 50px;
+}
+
+.pink {
+  background: hotpink;
+}
+</style>
+<script src="/common/reftest-wait.js"></script>
+<script src="/common/worklet-reftest.js"></script>
+
+<div class="container">
+  <!-- This tests that the "layout()" grandchildren floats within the don't interact with each other. -->
+  <div class="test">
+    <div class="inflow">
+      <div class="float pink"></div>
+    </div>
+    <div class="inflow">
+      <div class="float pink"></div>
+    </div>
+  </div>
+</div>
+
+<div class="container">
+  <!-- This tests that the "layout()" children margins interact as if they are new formatting contexts. -->
+  <div class="test">
+    <div class="inflow pink">
+      <div style="margin-bottom: 50px;"></div>
+    </div>
+    <div class="inflow pink">
+      <div style="margin-top: 50px;"></div>
+    </div>
+  </div>
+</div>
+
+<script id="code" type="text/worklet">
+registerLayout('registered', class {
+  *intrinsicSizes() {}
+  *layout() {}
+});
+</script>
+
+<script>
+importWorkletAndTerminateTestAfterAsyncPaint(CSS.layoutWorklet, document.getElementById('code').textContent);
+</script>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-unregistered-ref.html b/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-unregistered-ref.html
new file mode 100644
index 00000000000..fc43ad2fec9
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-unregistered-ref.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<style>
+.container {
+  margin: 20px 0;
+  border: solid 2px;
+  width: 100px;
+}
+
+.inflow {
+  height: 40px;
+}
+</style>
+
+<div class="container">
+  <div class="inflow"></div>
+  <div class="inflow" style="background: hotpink"></div>
+  <div class="inflow"></div>
+</div>
+
+<div class="container">
+  <div class="inflow"></div>
+  <div class="inflow" style="background: hotpink"></div>
+  <div class="inflow"></div>
+</div>
+
+<div class="container">
+  <div class="inflow" style="background: hotpink"></div>
+  <div class="inflow" style="background: green"></div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-unregistered.https.html b/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-unregistered.https.html
new file mode 100644
index 00000000000..48d7aa72bdf
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-layout-api/box-tree-unregistered.https.html
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.css-houdini.org/css-layout-api/#layout-api-box-tree">
+<link rel="match" href="box-tree-unregistered-ref.html">
+<meta name="assert" content="This test checks that an unregistered layout() works the same as a normal flow-root." />
+<style>
+@supports (display: layout(unregistered)) {
+  .test {
+    display: layout(unregistered);
+  }
+}
+
+.container {
+  margin: 20px 0;
+  border: solid 2px;
+  width: 100px;
+}
+
+.float {
+  float: left;
+  width: 100%;
+  height: 40px;
+  background: hotpink;
+}
+
+.inflow {
+  height: 40px;
+  background: hotpink;
+}
+</style>
+
+<div class="container">
+  <!-- This tests that the "layout()" margins don't collapse with its children. -->
+  <div class="test" style="margin: 20px 0">
+    <div class="inflow" style="margin: 20px 0"></div>
+  </div>
+</div>
+
+<div class="container">
+  <!-- This tests that the "layout()" grows to fit child floats. -->
+  <div class="test">
+    <div class="float" style="margin: 40px 0"></div>
+  </div>
+</div>
+
+<div class="container">
+  <!-- This tests that a float does not intrude into "layout()" box. -->
+  <div class="float"></div>
+  <div class="test" style="width: 100%; height: 40px; background: green;"></div>
+</div>
diff --git a/tests/wpt/web-platform-tests/css/css-scoping/slotted-link.html b/tests/wpt/web-platform-tests/css/css-scoping/slotted-link.html
new file mode 100644
index 00000000000..c06c96143ba
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-scoping/slotted-link.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Scoping: ::slotted :link</title>
+<link rel="author" title="Rune Lillesveen" href="mailto:futhark@chromium.org">
+<link rel="help" href="https://drafts.csswg.org/css-scoping/#slotted-pseudo">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="host"><a id="a" href="#notvisited">This link should be green.</a></div>
+<script>
+  let root = host.attachShadow({mode:"open"});
+  root.innerHTML = `
+  <style>
+    ::slotted(:link) { color:green }
+    ::slotted(:visited) { color:red }
+  </style>
+  <slot></slot>`;
+
+  test(() => {
+    assert_equals(getComputedStyle(a).color, "rgb(0, 128, 0)", "Unvisited link should be green.");
+  }, "Check that we match :link and not :visited for slotted anchor.");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-tables/internal-containing-block-001.html b/tests/wpt/web-platform-tests/css/css-tables/internal-containing-block-001.html
new file mode 100644
index 00000000000..a8745487b67
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-tables/internal-containing-block-001.html
@@ -0,0 +1,60 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<link rel="author" title="David Grogan" href="dgrogan@chromium.org">
+<link rel="help" href="https://drafts.csswg.org/css-tables-3/#abspos-boxes-in-table-internal">
+<link rel="help" href="https://www.w3.org/TR/css-position-3/#valdef-position-absolute">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<link rel="bookmark" href="https://bugs.chromium.org/p/chromium/issues/detail?id=798164" />
+<meta name="flags" content="" />
+<meta name="assert" content="A table-row with position:relative establishes a
+containing block for a position:absolute descendent of a table-cell, and the
+descendent is positioned correctly." />
+<title>
+relpos table-row establishes containing block for abspos
+</title>
+
+<style>
+tr {
+  position: relative;
+}
+
+div.abspos {
+  position: absolute;
+  height: 50px;
+  width: 100px;
+  background: green;
+}
+
+div.static {
+  height: 50px;
+  width: 100px;
+  background:red;
+}
+
+td, tr {
+  margin:0px;
+  padding:0px;
+}
+
+table {
+  border-collapse:collapse;
+}
+</style>
+
+<p>Test passes if there is a filled green square and <strong>no red</strong>.
+</p>
+
+<table>
+  <tr>
+    <td>
+      <div class="abspos"></div>
+      <div class="static"></div>
+    </td>
+  </tr>
+  <tr>
+    <td>
+      <div class="abspos"></div>
+      <div class="static"></div>
+    </td>
+  </tr>
+</table>
diff --git a/tests/wpt/web-platform-tests/css/css-transforms/animation/scale-interpolation.html b/tests/wpt/web-platform-tests/css/css-transforms/animation/scale-interpolation.html
index da25d3afb7c..942b80a309d 100644
--- a/tests/wpt/web-platform-tests/css/css-transforms/animation/scale-interpolation.html
+++ b/tests/wpt/web-platform-tests/css/css-transforms/animation/scale-interpolation.html
@@ -28,13 +28,13 @@
       test_interpolation({
         property: 'scale',
         from: '26 17 9',
-        to: '2',
+        to: '2 1',
       }, [
         {at: -1, expect: '50 33 17'},
         {at: 0, expect: '26 17 9'},
         {at: 0.125, expect: '23 15 8'},
         {at: 0.875, expect: '5 3 2'},
-        {at: 1, expect: '2'},
+        {at: 1, expect: '2 1'},
         {at: 2, expect: '-22 -15 -7'}
       ]);
 
diff --git a/tests/wpt/web-platform-tests/css/css-transforms/css-transform-property-existence.html b/tests/wpt/web-platform-tests/css/css-transforms/css-transform-property-existence.html
index 75e1a1b3396..5885db272bb 100644
--- a/tests/wpt/web-platform-tests/css/css-transforms/css-transform-property-existence.html
+++ b/tests/wpt/web-platform-tests/css/css-transforms/css-transform-property-existence.html
@@ -14,7 +14,7 @@
     <div id="log"></div>
     <script>
       test(function() {
-        assert_not_equals(document.getElementById("test").style.transfor, undefined, "expect transform is not undefined");
+        assert_not_equals(document.getElementById("test").style.transform, undefined, "expect transform is not undefined");
       }, "Check the existence of transform.");
 
       test(function() {
diff --git a/tests/wpt/web-platform-tests/css/css-transforms/individual-transform/individual-transform-1-ref.html b/tests/wpt/web-platform-tests/css/css-transforms/individual-transform/individual-transform-1-ref.html
index 8a568d25d92..9271c77cb67 100644
--- a/tests/wpt/web-platform-tests/css/css-transforms/individual-transform/individual-transform-1-ref.html
+++ b/tests/wpt/web-platform-tests/css/css-transforms/individual-transform/individual-transform-1-ref.html
@@ -24,7 +24,7 @@
         left: 100px;
         width: 50px;
         height: 100px;
-        transform: scaleX(2);
+        transform: scale(2, 2);
       }
       .translate_1 {
         left: 150px;
diff --git a/tests/wpt/web-platform-tests/css/css-transforms/parsing/rotate-parsing-invalid.html b/tests/wpt/web-platform-tests/css/css-transforms/parsing/rotate-parsing-invalid.html
index 2597a4230f7..8326db38e68 100644
--- a/tests/wpt/web-platform-tests/css/css-transforms/parsing/rotate-parsing-invalid.html
+++ b/tests/wpt/web-platform-tests/css/css-transforms/parsing/rotate-parsing-invalid.html
@@ -17,6 +17,12 @@ test_invalid_value("rotate", "100px");
 test_invalid_value("rotate", "100 400deg");
 test_invalid_value("rotate", "100 200 400deg");
 test_invalid_value("rotate", "100 200 300 500 400deg");
+
+test_invalid_value("rotate", "x y 45deg");
+test_invalid_value("rotate", "45deg x y");
+test_invalid_value("rotate", "z");
+test_invalid_value("rotate", "1 2");
+test_invalid_value("rotate", "1 2 3");
 </script>
 </body>
 </html>
diff --git a/tests/wpt/web-platform-tests/css/css-transforms/parsing/rotate-parsing-valid.html b/tests/wpt/web-platform-tests/css/css-transforms/parsing/rotate-parsing-valid.html
index a33f0fd449c..b2e57495a87 100644
--- a/tests/wpt/web-platform-tests/css/css-transforms/parsing/rotate-parsing-valid.html
+++ b/tests/wpt/web-platform-tests/css/css-transforms/parsing/rotate-parsing-valid.html
@@ -17,6 +17,16 @@ test_valid_value("rotate", "none");
 test_valid_value("rotate", "0deg");
 
 test_valid_value("rotate", "100 200 300 400grad");
+test_valid_value("rotate", "400grad 100 200 300", "100 200 300 400grad");
+
+test_valid_value("rotate", "x 400grad", "1 0 0 400grad");
+test_valid_value("rotate", "400grad x", "1 0 0 400grad");
+
+test_valid_value("rotate", "y 400grad", "0 1 0 400grad");
+test_valid_value("rotate", "400grad y", "0 1 0 400grad");
+
+test_valid_value("rotate", "z 400grad", "0 0 1 400grad");
+test_valid_value("rotate", "400grad z", "0 0 1 400grad");
 </script>
 </body>
 </html>
diff --git a/tests/wpt/web-platform-tests/css/css-transforms/transforms-support-calc.html b/tests/wpt/web-platform-tests/css/css-transforms/transforms-support-calc.html
index 19bacd96261..71a046f56b0 100644
--- a/tests/wpt/web-platform-tests/css/css-transforms/transforms-support-calc.html
+++ b/tests/wpt/web-platform-tests/css/css-transforms/transforms-support-calc.html
@@ -31,7 +31,7 @@
 
 test(function(){
   target.style = 'translate: calc(30px + 20%) calc(-200px + 100%);';
-  assert_equals(getComputedStyle(target).translate, '90px 0px');
+  assert_equals(getComputedStyle(target).translate, 'calc(30px + 20%) calc(-200px + 100%)');
 }, 'translate supports calc');
 
 test(function(){
diff --git a/tests/wpt/web-platform-tests/css/css-transforms/translate-getComputedStyle.html b/tests/wpt/web-platform-tests/css/css-transforms/translate-getComputedStyle.html
new file mode 100644
index 00000000000..1e6759d1b0c
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-transforms/translate-getComputedStyle.html
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>CSS Transform Module Level 2: translate getComputedStyle</title>
+  <link rel="author" title="Eric Willigers" href="mailto:ericwilligers@chromium.org">
+  <link rel="help" href="https://drafts.csswg.org/css-transforms-2/#propdef-translate">
+  <meta name="assert" content="translate computed style does not resolve percentages.">
+  <style type="text/css">
+    #container {
+      transform-style: preserve-3d;;
+    }
+    #first {
+      font-size: 10px;
+      translate: 10px 2em;
+    }
+    #second {
+      translate: 30% 40% 50px;
+    }
+    #third {
+      font-size: 10px;
+      width: 98px;
+      height: 76px;
+      translate: calc(7em + 80%) -9em;
+    }
+  </style>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+  <div id="container">
+    <div id="first"></div>
+    <div id="second"></div>
+    <div id="third"></div>
+  </div>
+  <script>
+    'use strict';
+    function getTranslateFor(id) {
+      return window.getComputedStyle(document.getElementById(id)).getPropertyValue("translate");
+    }
+
+    test(function() {
+      assert_equals(getTranslateFor("first"), "10px 20px");
+      assert_equals(getTranslateFor("second"), "30% 40% 50px");
+      assert_equals(getTranslateFor("third"), "calc(70px + 80%) -90px");
+    }, "computed style for translate");
+  </script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/resources/testhelper.js b/tests/wpt/web-platform-tests/css/css-typed-om/resources/testhelper.js
index 0099da2b460..91af64cfca6 100644
--- a/tests/wpt/web-platform-tests/css/css-typed-om/resources/testhelper.js
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/resources/testhelper.js
@@ -57,6 +57,9 @@ function assert_style_value_equals(a, b) {
     case 'CSSSkewX':
       assert_style_value_equals(a.ax, b.ax);
       break;
+    case 'CSSSkewY':
+      assert_style_value_equals(a.ay, b.ay);
+      break;
     case 'CSSPerspective':
       assert_style_value_equals(a.length, b.length);
       break;
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-normalization/transformvalue-normalization.tentative.html b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-normalization/transformvalue-normalization.tentative.html
index 626c4bb717b..9157ae89241 100644
--- a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-normalization/transformvalue-normalization.tentative.html
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-normalization/transformvalue-normalization.tentative.html
@@ -140,7 +140,7 @@ const gTestCases = [
   },
   {
     cssText: 'skewY(90deg)',
-    expected: new CSSSkew(CSS.deg(0), CSS.deg(90)),
+    expected: new CSSSkewY(CSS.deg(90)),
     desc: 'skewY()'
   },
   {
@@ -158,13 +158,14 @@ for (const {cssText, expected, desc} of gTestCases) {
 
 test(t => {
   test_transform_normalization(t,
-      'translate(1px) rotateX(90deg) perspective(1px) skew(90deg) skewX(20deg) scale3d(1, 2, 3)',
+      'translate(1px) rotateX(90deg) perspective(1px) skew(90deg) skewX(20deg) skewY(30deg) scale3d(1, 2, 3)',
       new CSSTransformValue([
         new CSSTranslate(CSS.px(1), CSS.px(0)),
         new CSSRotate(CSS.number(1), CSS.number(0), CSS.number(0), CSS.deg(90)),
         new CSSPerspective(CSS.px(1)),
         new CSSSkew(CSS.deg(90), CSS.deg(0)),
         new CSSSkewX(CSS.deg(20)),
+        new CSSSkewY(CSS.deg(30)),
         new CSSScale(CSS.number(1), CSS.number(2), CSS.number(3)),
       ]));
 }, 'Normalizing a <transform-list> returns a CSSTransformValue containing all the transforms');
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-serialization/cssTransformValue.tentative.html b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-serialization/cssTransformValue.tentative.html
index 48926ad24d5..dc87e81271f 100644
--- a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-serialization/cssTransformValue.tentative.html
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-serialization/cssTransformValue.tentative.html
@@ -54,6 +54,11 @@ const gTestCases = [
     cssText: 'skewX(90deg)',
     desc: 'CSSSkewX'
   },
+  {
+    value: new CSSSkewY(CSS.deg(90)),
+    cssText: 'skewY(90deg)',
+    desc: 'CSSSkewY'
+  },
   {
     value: new CSSPerspective(CSS.px(1)),
     cssText: 'perspective(1px)',
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssSkewY.tentative.html b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssSkewY.tentative.html
new file mode 100644
index 00000000000..643d2f686bb
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssSkewY.tentative.html
@@ -0,0 +1,62 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSSSkewY tests</title>
+<link rel="help" href="https://drafts.css-houdini.org/css-typed-om-1/#cssskewy">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../resources/testhelper.js"></script>
+<script>
+'use strict';
+
+const gInvalidTestCases = [
+  { value: 'auto', desc: 'a keyword'},
+  { value: 3.14, desc: 'a double'},
+  { value: 0, desc: 'a unitless zero'},
+  { value: '10deg', desc: 'a string angle'},
+  { value: CSS.number(10), desc: 'a number CSSUnitValue'},
+  { value: CSS.s(10), desc: 'a time dimension CSSUnitValue'},
+  { value: new CSSMathSum(CSS.px(1)), desc: 'a CSSMathValue of length type' },
+];
+
+for (const {value, desc} of gInvalidTestCases) {
+  test(() => {
+    assert_throws(new TypeError(), () => new CSSSkewY(value));
+  }, 'Constructing a CSSSkewY with ' + desc + ' throws a TypeError');
+}
+
+for (const {value, desc} of gInvalidTestCases) {
+  test(() => {
+    let skewY = new CSSSkewY(CSS.deg(0));
+    assert_throws(new TypeError(), () => skewY.ay = value);
+    assert_style_value_equals(skewY.ay, CSS.deg(0));
+  }, 'Updating CSSSkewY.ay with ' + desc + ' throws a TypeError');
+}
+
+const gValidTestCases = [
+  { value: CSS.deg(-3.14), desc: 'an angle CSSUnitValue' },
+  { value: new CSSMathSum(CSS.deg(1)), desc: 'a CSSMathValue of angle type' },
+];
+
+for (const {value: ay, desc: ayDesc} of gValidTestCases) {
+  test(() => {
+    const skewY = new CSSSkewY(ay);
+    assert_equals(skewY.ay, ay);
+    assert_true(skewY.is2D);
+  }, 'CSSSkewY can be constructed from ' + ayDesc);
+}
+
+for (const {value, desc} of gValidTestCases) {
+  test(() => {
+    let skewY = new CSSSkewY(CSS.deg(0));
+    skewY.ay = value;
+    assert_style_value_equals(skewY.ay, value);
+  }, 'CSSSkewY.ay can be updated to ' + desc);
+}
+
+test(() => {
+  let skewY = new CSSSkewY(CSS.deg(0));
+  skewY.is2D = false;
+  assert_true(skewY.is2D);
+}, 'Modifying skewY.is2D is a no-op');
+
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix-relative-units.html b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix-relative-units.html
new file mode 100644
index 00000000000..67b63a6b666
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix-relative-units.html
@@ -0,0 +1,27 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSSTransformComponent.toMatrix with Relative Units</title>
+<link rel="help" href="https://drafts.css-houdini.org/css-typed-om-1/#dom-csstransformcomponent-tomatrix">
+<meta name="assert" content="Test CSSTransformComponent.toMatrix throws when given relative units" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../resources/testhelper.js"></script>
+<script>
+'use strict';
+
+test(() => {
+  assert_throws(new TypeError(), () => {
+    return new CSSTranslate(
+      new CSSUnitValue(1, 'px'),
+      new CSSUnitValue(1, 'em')
+    ).toMatrix();
+  });
+}, 'CSSTranslate.toMatrix() containing relative units throws TypeError');
+
+test(() => {
+  assert_throws(new TypeError(), () => {
+    return new CSSPerspective(new CSSUnitValue(1, 'em')).toMatrix();
+  });
+}, 'CSSPerspective.toMatrix() containing relative units throws TypeError');
+
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix.html b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix.html
new file mode 100644
index 00000000000..14d819be40a
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformComponent-toMatrix.html
@@ -0,0 +1,86 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSSTransformComponent.toMatrix tests</title>
+<link rel="help" href="https://drafts.css-houdini.org/css-typed-om-1/#dom-csstransformcomponent-tomatrix">
+<meta name="assert" content="Test CSSTransformComponent.toMatrix for each type of component" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../resources/testhelper.js"></script>
+<script>
+'use strict';
+
+const gEpsilon = 1e-6;
+
+test(() => {
+  const component = new CSSTranslate(
+    new CSSUnitValue(1, 'px'),
+    new CSSUnitValue(2, 'px'),
+    new CSSUnitValue(3, 'px')
+  );
+  const expectedMatrix = (new DOMMatrixReadOnly()).translate(1, 2, 3);
+  assert_matrix_approx_equals(component.toMatrix(), expectedMatrix, 1e-8);
+}, 'CSSTranslate.toMatrix() returns correct matrix');
+
+test(() => {
+  const component = new CSSRotate(
+    new CSSUnitValue(1, 'number'),
+    new CSSUnitValue(2, 'number'),
+    new CSSUnitValue(3, 'number'),
+    new CSSUnitValue(90, 'deg')
+  );
+  const expectedMatrix = (new DOMMatrixReadOnly()).rotateAxisAngle(1, 2, 3, 90);
+  assert_matrix_approx_equals(component.toMatrix(), expectedMatrix, gEpsilon);
+}, 'CSSRotate.toMatrix() returns correct matrix');
+
+test(() => {
+  const component = new CSSScale(1, 2, 3);
+  const expectedMatrix = (new DOMMatrixReadOnly()).scale(1, 2, 3);
+  assert_matrix_approx_equals(component.toMatrix(), expectedMatrix, gEpsilon);
+}, 'CSSScale.toMatrix() returns correct matrix');
+
+test(() => {
+  const alpha = 10, beta = 20;
+  const component = new CSSSkew(
+    new CSSUnitValue(alpha, 'rad'),
+    new CSSUnitValue(beta, 'rad')
+  );
+  const expectedMatrix = new DOMMatrixReadOnly(
+        [1, Math.tan(beta), 0, 0, Math.tan(alpha), 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1]);
+  assert_matrix_approx_equals(component.toMatrix(), expectedMatrix, gEpsilon);
+}, 'CSSSkew.toMatrix() returns correct matrix');
+
+test(() => {
+  const component = new CSSSkewX(
+    new CSSUnitValue(10, 'rad'),
+  );
+  const expectedMatrix = (new DOMMatrixReadOnly()).skewX(10);
+  assert_matrix_approx_equals(component.toMatrix(), expectedMatrix, gEpsilon);
+}, 'CSSSkewX.toMatrix() returns correct matrix');
+
+test(() => {
+  const component = new CSSSkewY(
+    new CSSUnitValue(10, 'rad'),
+  );
+  const expectedMatrix = (new DOMMatrixReadOnly()).skewY(10);
+  assert_matrix_approx_equals(component.toMatrix(), expectedMatrix, gEpsilon);
+}, 'CSSSkewY.toMatrix() returns correct matrix');
+
+test(() => {
+  const length = 10;
+  const component = new CSSPerspective(new CSSUnitValue(length, 'px'));
+  const expectedMatrix = new DOMMatrixReadOnly(
+        [1, 0, 0, 0,
+         0, 1, 0, 0,
+         0, 0, 1, -1/length,
+         0, 0, 0, 1]);
+  assert_matrix_approx_equals(component.toMatrix(), expectedMatrix, gEpsilon);
+}, 'CSSPerspective.toMatrix() returns correct matrix');
+
+test(() => {
+  const matrix = new DOMMatrixReadOnly(
+          [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]);
+  const component = new CSSMatrixComponent(matrix);
+  assert_matrix_approx_equals(component.toMatrix(), matrix, gEpsilon);
+}, 'CSSMatrixComponent.toMatrix() returns correct matrix');
+
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformValue-toMatrix.html b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformValue-toMatrix.html
new file mode 100644
index 00000000000..c0e0bbc270d
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformValue-toMatrix.html
@@ -0,0 +1,52 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSSTransformValue.toMatrix</title>
+<link rel="help" href="https://drafts.css-houdini.org/css-typed-om-1/#dom-csstransformcomponent-tomatrix">
+<meta name="assert" content="Test CSSTransformValue.toMatrix multiplies component matrices" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../resources/testhelper.js"></script>
+<script>
+'use strict';
+
+const gEpsilon = 1e-6;
+
+test(() => {
+  const transformMatrix = new DOMMatrixReadOnly([1, 1, 1, 1, 1, 1]);
+  const transformArray = [
+    new CSSScale(2, 2),
+    new CSSMatrixComponent(transformMatrix),
+    new CSSScale(5, 6)
+  ];
+
+  let expectedMatrix = new DOMMatrix();
+  expectedMatrix.scaleSelf(2, 2);
+  expectedMatrix.multiplySelf(transformMatrix);
+  expectedMatrix.scaleSelf(5, 6);
+
+  const transform = new CSSTransformValue(transformArray);
+  assert_matrix_approx_equals(transform.toMatrix(), expectedMatrix, gEpsilon);
+}, 'CSSTransformValue.toMatrix() multiplies its component matrices');
+
+test(() => {
+  const transformMatrix = new DOMMatrixReadOnly([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]);
+  let transformArray = [
+    new CSSTranslate(CSS.px(1), CSS.px(1), CSS.px(1)),
+    new CSSRotate(1, 2, 3, CSS.deg(90)),
+    new CSSScale(2, 3, 2),
+    new CSSMatrixComponent(transformMatrix),
+  ];
+
+  transformArray.forEach(transform => transform.is2D = true);
+
+  let expectedMatrix = new DOMMatrix();
+  expectedMatrix.translateSelf(1, 1);
+  expectedMatrix.rotateSelf(90);
+  expectedMatrix.scaleSelf(2, 3);
+  expectedMatrix.multiplySelf(new DOMMatrixReadOnly([1, 2, 5, 6, 13, 14]));
+
+  const transform = new CSSTransformValue(transformArray);
+  assert_matrix_approx_equals(transform.toMatrix(), expectedMatrix, gEpsilon);
+}, 'CSSTransformValue.toMatrix() respects is2D changes in its components');
+
+</script>
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformValue.tentative.html b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformValue.tentative.html
index b16d7369c2c..bc1ace633ad 100644
--- a/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformValue.tentative.html
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/stylevalue-subclasses/cssTransformValue.tentative.html
@@ -9,8 +9,6 @@
 <script>
 'use strict';
 
-const EPSILON = 1e-6;
-
 test(() => {
   assert_throws(new TypeError(), () => new CSSTransformValue());
   assert_throws(new TypeError(), () => new CSSTransformValue([]));
@@ -51,106 +49,6 @@ test(() => {
   assert_equals(transform.is2D, true);
 }, 'CSSTransformValue.is2D is readonly');
 
-test(() => {
-  assert_throws(new TypeError(), () => new CSSTransformValue([new CSSTranslate(CSS.px(1), CSS.em(1))]).toMatrix());
-  assert_throws(new TypeError(), () => new CSSTransformValue([new CSSPerspective(CSS.em(1))]).toMatrix());
-}, 'Calling CSSTransformValue.toMatrix containing relative units throws TypeError');
-
-test(() => {
-  const transform = new CSSTransformValue([
-    new CSSTranslate(CSS.px(1), CSS.px(2), CSS.px(3))
-  ]);
-  const expectedMatrix = (new DOMMatrixReadOnly()).translate(1, 2, 3);
-  assert_matrix_approx_equals(transform.toMatrix(), expectedMatrix, 1e-8);
-}, 'CSSTransformValue.toMatrix returns correct matrix for CSSTranslate');
-
-test(() => {
-  const transform = new CSSTransformValue([
-    new CSSRotate(CSS.number(1), CSS.number(2), CSS.number(3), CSS.deg(90))
-  ]);
-  const expectedMatrix = (new DOMMatrixReadOnly()).rotateAxisAngle(1, 2, 3, 90);
-  assert_matrix_approx_equals(transform.toMatrix(), expectedMatrix, EPSILON);
-}, 'CSSTransformValue.toMatrix returns correct matrix for CSSRotate');
-
-test(() => {
-  const transform = new CSSTransformValue([
-      new CSSScale(CSS.number(1), CSS.number(2), CSS.number(3))
-  ]);
-  const expectedMatrix = (new DOMMatrixReadOnly()).scale(1, 2, 3);
-  assert_matrix_approx_equals(transform.toMatrix(), expectedMatrix, EPSILON);
-}, 'CSSTransformValue.toMatrix returns correct matrix for CSSScale');
-
-test(() => {
-  const alpha = 10;
-  const beta = 20;
-  const transform = new CSSTransformValue([
-      new CSSSkew(CSS.rad(alpha), CSS.rad(beta))
-  ]);
-  const expectedMatrix = new DOMMatrixReadOnly(
-        [1, Math.tan(beta), 0, 0, Math.tan(alpha), 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1]);
-  assert_matrix_approx_equals(transform.toMatrix(), expectedMatrix, EPSILON);
-}, 'CSSTransformValue.toMatrix returns correct matrix for CSSSkew');
-
-test(() => {
-  const length = 10;
-  const transform = new CSSTransformValue([
-      new CSSPerspective(CSS.px(length))
-  ]);
-  const expectedMatrix = new DOMMatrixReadOnly(
-        [1, 0, 0, 0,
-         0, 1, 0, 0,
-         0, 0, 1, -1/length,
-         0, 0, 0, 1]);
-  assert_matrix_approx_equals(transform.toMatrix(), expectedMatrix, EPSILON);
-}, 'CSSTransformValue.toMatrix returns correct matrix for CSSPerspective');
-
-test(() => {
-  const matrix = new DOMMatrixReadOnly(
-          [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]);
-  const transform = new CSSTransformValue([
-      new CSSMatrixComponent(matrix)
-  ]);
-  assert_matrix_approx_equals(transform.toMatrix(), matrix, EPSILON);
-}, 'CSSTransformValue.toMatrix returns correct matrix for CSSMatrixComponent');
-
-test(() => {
-  const transformMatrix = new DOMMatrixReadOnly([1, 1, 1, 1, 1, 1]);
-  const transformArray = [
-    new CSSScale(2, 2),
-    new CSSMatrixComponent(transformMatrix),
-    new CSSScale(5, 6)
-  ];
-
-  let expectedMatrix = new DOMMatrix();
-  expectedMatrix.scaleSelf(2, 2);
-  expectedMatrix.multiplySelf(transformMatrix);
-  expectedMatrix.scaleSelf(5, 6);
-
-  const transform = new CSSTransformValue(transformArray);
-  assert_matrix_approx_equals(transform.toMatrix(), expectedMatrix, EPSILON);
-}, 'CSSTransformValue.toMatrix multiplies its component matrices');
-
-test(() => {
-  const transformMatrix = new DOMMatrixReadOnly([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]);
-  let transformArray = [
-    new CSSTranslate(CSS.px(1), CSS.px(1), CSS.px(1)),
-    new CSSRotate(1, 2, 3, CSS.deg(90)),
-    new CSSScale(2, 3, 2),
-    new CSSMatrixComponent(transformMatrix),
-  ];
-
-  transformArray.forEach(transform => transform.is2D = true);
-
-  let expectedMatrix = new DOMMatrix();
-  expectedMatrix.translateSelf(1, 1);
-  expectedMatrix.rotateSelf(90);
-  expectedMatrix.scaleSelf(2, 3);
-  expectedMatrix.multiplySelf(new DOMMatrixReadOnly([1, 2, 5, 6, 13, 14]));
-
-  const transform = new CSSTransformValue(transformArray);
-  assert_matrix_approx_equals(transform.toMatrix(), expectedMatrix, EPSILON);
-}, 'CSSTransformValue.toMatrix respects is2D changes in its components');
-
 test(() => {
   const transformArray = [
     new CSSScale(2, 2),
diff --git a/tests/wpt/web-platform-tests/css/css-typed-om/the-stylepropertymap/properties/resources/testsuite.js b/tests/wpt/web-platform-tests/css/css-typed-om/the-stylepropertymap/properties/resources/testsuite.js
index 693911f8b15..42cd2b08900 100644
--- a/tests/wpt/web-platform-tests/css/css-typed-om/the-stylepropertymap/properties/resources/testsuite.js
+++ b/tests/wpt/web-platform-tests/css/css-typed-om/the-stylepropertymap/properties/resources/testsuite.js
@@ -1,3 +1,50 @@
+const gTestSyntax = {
+  '0': {
+    description: 'unitless zero',
+    set: true,
+    examples: [
+      new CSSUnitValue(0, 'number'),
+    ],
+  },
+  '<length>': {
+    description: 'a length',
+    get: true,
+    set: true,
+    examples: [
+      new CSSUnitValue(0, 'px'),
+      new CSSUnitValue(-3.14, 'em'),
+      new CSSUnitValue(3.14, 'cm'),
+    ],
+  },
+  '<percentage>': {
+    description: 'a percent',
+    get: true,
+    set: true,
+    examples: [
+      new CSSUnitValue(0, 'percent'),
+      new CSSUnitValue(-3.14, 'percent'),
+      new CSSUnitValue(3.14, 'percent'),
+    ],
+  },
+  '<time>': {
+    description: 'a time',
+    get: true,
+    set: true,
+    examples: [
+      new CSSUnitValue(0, 's'),
+      new CSSUnitValue(-3.14, 'ms'),
+      new CSSUnitValue(3.14, 's'),
+    ],
+  },
+  '<ident>': {
+    description: 'a CSSKeywordValue',
+    set: true,
+    get: true,
+    // user-specified examples
+    examples: null,
+  },
+};
+
 function testGet(propertyName, values, description) {
   test(t => {
     let element = createDivWithStyle(t);
@@ -27,36 +74,42 @@ function testSet(propertyName, values, description) {
   }, `Can set '${propertyName}' to ${description}`);
 }
 
-function testGetSet(propertyName, values, description) {
-  testGet(propertyName, values, description);
-  testSet(propertyName, values, description);
+function testSetInvalid(propertyName, values, description) {
+  test(t => {
+    let element = createDivWithStyle(t);
+    let styleMap = element.attributeStyleMap;
+
+    for (const styleValue of values) {
+      assert_throws(new TypeError(), () => styleMap.set(propertyName, styleValue));
+    }
+  }, `Setting '${propertyName}' to ${description} throws TypeError`);
 }
 
 function runPropertyTests(propertyName, testCases) {
-  for (const testCase of testCases) {
-    if (testCase.specified == '0') {
-      testSet(propertyName, [
-        new CSSUnitValue(0, 'number'),
-      ], 'unitless zero');
-    } else if (testCase.specified === '<length>') {
-      testGetSet(propertyName, [
-        new CSSUnitValue(0, 'px'),
-        new CSSUnitValue(-3.14, 'em'),
-        new CSSUnitValue(3.14, 'cm'),
-      ], 'a length CSSUnitValue');
-    } else if (testCase.specified == '<percentage>') {
-      testGetSet(propertyName, [
-        new CSSUnitValue(0, 'percent'),
-        new CSSUnitValue(-3.14, 'percent'),
-        new CSSUnitValue(3.14, 'percent'),
-      ], 'a percent CSSUnitValue');
-    } else if (testCase.specified == '<ident>') {
-      if (!testCase.examples) {
-        throw new Error('<ident> tests require examples');
-      }
+  let productionsTested = new Set();
 
-      testGetSet(propertyName, testCase.examples,
-        'a CSSKeywordValue');
+  for (const testCase of testCases) {
+    const syntax = gTestSyntax[testCase.specified];
+    if (!syntax)
+      throw new Error(`'${testCase.specified}' is not a valid production`);
+
+    const examples = testCase.examples || syntax.examples;
+    if (!examples)
+      throw new Error(`'${testCase.specified}' tests require explicit examples`);
+
+    if (syntax.get)
+      testGet(propertyName, examples, syntax.description);
+    if (syntax.set)
+      testSet(propertyName, examples, syntax.description);
+
+    productionsTested.add(testCase.specified);
+  }
+
+  // Also test that styleMap.set rejects invalid CSSStyleValues.
+  for (const [production, syntax] of Object.entries(gTestSyntax)) {
+    if (!productionsTested.has(production)) {
+      if (syntax.set && syntax.examples)
+        testSetInvalid(propertyName, syntax.examples, syntax.description);
     }
   }
 }
diff --git a/tests/wpt/web-platform-tests/css/cssom/css-style-attr-decl-block.html b/tests/wpt/web-platform-tests/css/cssom/css-style-attr-decl-block.html
new file mode 100644
index 00000000000..9b45d66f4ff
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/cssom/css-style-attr-decl-block.html
@@ -0,0 +1,133 @@
+<!DOCTYPE html>
+<meta charset="UTF-8">
+<link rel="author" title="Xidorn Quan" href="mailto:me@upsuper.org">
+<link rel="help" href="https://drafts.csswg.org/cssom-1/#css-declaration-blocks">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body>
+<script>
+function createTestElement(style) {
+  let wrapper = document.createElement("div");
+  wrapper.innerHTML = `<div id="test" style="${style}"></div>`;
+  return wrapper.querySelector("#test");
+}
+
+test(function() {
+  let elem = createTestElement("z-index: 10;");
+  assert_equals(elem.style.cssText, "z-index: 10;");
+}, "Style attribute should create CSS declaration block based on its content");
+
+test(function() {
+  let elem = createTestElement("z-index: 20;");
+  let style = elem.style;
+  assert_equals(style.cssText, "z-index: 20;");
+  function assert_css_text(value, action) {
+    assert_equals(style.cssText, value, "CSS declaration block after " + action);
+  }
+  elem.setAttribute("style", "z-index: 21;");
+  assert_css_text("z-index: 21;", "changing the style attribute");
+  elem.removeAttribute("style");
+  assert_css_text("", "removing the style attribute");
+  elem.setAttribute("style", "position: absolute;");
+  assert_css_text("position: absolute;", "adding style attribute again");
+}, "Changes to style attribute should reflect on CSS declaration block");
+
+test(function() {
+  let elem = createTestElement("z-index: 30;");
+  let style = elem.style;
+  assert_equals(style.cssText, "z-index: 30;");
+  function assert_attr(value, action) {
+    assert_equals(elem.getAttribute("style"), value, "style attribute after " + action);
+  }
+  style.setProperty("z-index", "31");
+  assert_attr("z-index: 31;", "changing property in CSS declaration block");
+  style.removeProperty("z-index");
+  assert_attr("", "removing property from CSS declaration block");
+  style.setProperty("position", "absolute");
+  assert_attr("position: absolute;", "adding property to CSS declaration block");
+  style.cssText = "z-index: 32;";
+  assert_attr("z-index: 32;", "changing cssText");
+  style.cssText = "z-index: 33; invalid";
+  assert_attr("z-index: 33;", "changing cssText to a partial invalid value");
+}, "Changes to CSS declaration block should reflect on style attribute");
+
+test(function() {
+  let elem = createTestElement("z-index: 40;");
+  let style = elem.style;
+  assert_equals(style.cssText, "z-index: 40;");
+  // Create an observer for the element.
+  let observer = new MutationObserver(function() {});
+  observer.observe(elem, {attributes: true, attributeOldValue: true});
+  function assert_record_with_old_value(oldValue, action) {
+    let records = observer.takeRecords();
+    assert_equals(records.length, 1, "number of mutation records after " + action);
+    let record = records[0];
+    assert_equals(record.type, "attributes", "mutation type after " + action);
+    assert_equals(record.attributeName, "style", "mutated attribute after " + action);
+    assert_equals(record.oldValue, oldValue, "old value after " + action);
+  }
+  style.setProperty("z-index", "41");
+  assert_record_with_old_value("z-index: 40;", "changing property in CSS declaration block");
+  style.cssText = "z-index: 42;";
+  assert_record_with_old_value("z-index: 41;", "changing cssText");
+  style.cssText = "z-index: 42;";
+  assert_record_with_old_value("z-index: 42;", "changing cssText with the same content");
+  style.removeProperty("z-index");
+  assert_record_with_old_value("z-index: 42;", "removing property from CSS declaration block");
+  // Mutation to shorthand properties should also trigger only one mutation record.
+  style.setProperty("margin", "1px");
+  assert_record_with_old_value("", "adding shorthand property to CSS declaration block");
+  style.removeProperty("margin");
+  assert_record_with_old_value("margin: 1px;", "removing shorthand property from CSS declaration block");
+  // Final sanity check.
+  assert_equals(elem.getAttribute("style"), "");
+}, "Changes to CSS declaration block should queue mutation record for style attribute");
+
+test(function() {
+  let elem = createTestElement("z-index: 50; invalid");
+  let style = elem.style;
+  assert_equals(style.cssText, "z-index: 50;");
+  // Create an observer for the element.
+  let observer = new MutationObserver(function() {});
+  observer.observe(elem, {attributes: true});
+  function assert_no_record(action) {
+    let records = observer.takeRecords();
+    assert_true(records.length == 0, "expect no record after " + action);
+  }
+  style.setProperty("z-index", "invalid");
+  assert_no_record("setting invalid value to property");
+  // Longhand property.
+  style.removeProperty("position");
+  assert_no_record("removing non-existing longhand property");
+  style.setProperty("position", "");
+  assert_no_record("setting empty string to non-existing longhand property");
+  // Shorthand property.
+  style.removeProperty("margin");
+  assert_no_record("removing non-existing shorthand property");
+  style.setProperty("margin", "");
+  assert_no_record("setting empty string to non-existing shorthand property");
+  // Check that the value really isn't changed.
+  assert_equals(elem.getAttribute("style"), "z-index: 50; invalid",
+                "style attribute after removing non-existing properties");
+}, "Removing non-existing property or setting invalid value on CSS declaration block shouldn't queue mutation record");
+
+test(function() {
+  let elem = createTestElement("background-image: url(./);");
+  let style = elem.style;
+  let base = document.createElement("base");
+  base.href = "/";
+  document.body.appendChild(elem);
+  let originalComputedValue = getComputedStyle(elem).backgroundImage;
+  document.head.appendChild(base);
+  this.add_cleanup(() => {
+    document.head.removeChild(base);
+    document.body.removeChild(elem);
+  });
+  style.setProperty("background-color", "green");
+  assert_equals(getComputedStyle(elem).backgroundImage, originalComputedValue,
+                "getComputedStyle(elem).backgroundImage after setting background-color");
+  style.setProperty("background-image", "url(./)");
+  assert_not_equals(getComputedStyle(elem).backgroundImage, originalComputedValue,
+                    "getComputedStyle(elem).backgroundImage after setting background-image");
+}, "Changes to CSS declaration block after a base URL change");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/cssom/cssimportrule.html b/tests/wpt/web-platform-tests/css/cssom/cssimportrule.html
index 7267c9ad884..691f886aac1 100644
--- a/tests/wpt/web-platform-tests/css/cssom/cssimportrule.html
+++ b/tests/wpt/web-platform-tests/css/cssom/cssimportrule.html
@@ -14,16 +14,17 @@
     <style id="styleElement" type="text/css">
         @import url("support/a-green.css");
         @import url("support/a-green.css") screen;
+        @page { background-color: red; }
     </style>
 </head>
 <body>
     <div id="log"></div>
 
     <script type="text/javascript">
-        var rule, ruleWithMedia;
+        var styleSheet, ruleList, rule, ruleWithMedia;
         setup(function() {
-            var styleSheet = document.getElementById("styleElement").sheet;
-            var ruleList = styleSheet.cssRules;
+            styleSheet = document.getElementById("styleElement").sheet;
+            ruleList = styleSheet.cssRules;
             rule = ruleList[0];
             ruleWithMedia = ruleList[1];
         });
@@ -87,7 +88,18 @@
         test(function() {
             ruleWithMedia.media = "print";
             assert_equals(ruleWithMedia.media.mediaText, "print");
-        }, "MediaList mediaText attribute should be updated");
+        }, "CSSImportRule : MediaList mediaText attribute should be updated due to [PutForwards]");
+
+        test(function() {
+            var ruleWithPage = ruleList[2];
+            ruleWithPage.style = "background-color: green;"
+            assert_equals(ruleWithPage.style.cssText, "background-color: green;");
+        }, "CSSStyleDeclaration cssText attribute should be updated due to [PutForwards]");
+
+        test(function() {
+            styleSheet.media = "screen";
+            assert_equals(styleSheet.media.mediaText, "screen");
+        }, "StyleSheet : MediaList mediaText attribute should be updated due to [PutForwards]");
     </script>
 </body>
 </html>
diff --git a/tests/wpt/web-platform-tests/css/cssom/selectorText-modification-restyle-002.html b/tests/wpt/web-platform-tests/css/cssom/selectorText-modification-restyle-002.html
new file mode 100644
index 00000000000..a6b37c2cf0a
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/cssom/selectorText-modification-restyle-002.html
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<title>CSSOM: Modify selectorText in a shadow tree stylesheet</title>
+<link rel="author" title="Rune Lillesveen" href="mailto:futhark@chromium.org">
+<link rel="help" href="https://drafts.csswg.org/cssom/#dom-cssstylerule-selectortext">
+<link rel="help" href="https://drafts.csswg.org/css-scoping/#selectors">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+  #container { color: red }
+  .subtree * { color: pink }
+</style>
+<div id="container">
+  <div id="host"></div>
+</div>
+<script>
+  const root = host.attachShadow({mode:"open"});
+  root.innerHTML = "<style>nomatch { color: green }</style><div>Green</div>";
+  const div = root.querySelector("div");
+
+  test(() => {
+    assert_equals(getComputedStyle(div).color, "rgb(255, 0, 0)", "Color should initial be red.");
+  }, "Check initial color.");
+
+  test(() => {
+    // The combination of the .subtree and CSSOM selector style invalidations
+    // caused the Blink implementation to fail an assertion.
+    container.className = "subtree";
+    root.styleSheets[0].cssRules[0].selectorText = "div";
+    assert_equals(getComputedStyle(div).color, "rgb(0, 128, 0)", "Color should be green after stylesheet change.");
+  }, "Check that color changes correctly after shadow stylesheet selector and #container class is changed.");
+</script>
diff --git a/tests/wpt/web-platform-tests/css/mediaqueries/viewport-script-dynamic-ref.html b/tests/wpt/web-platform-tests/css/mediaqueries/viewport-script-dynamic-ref.html
new file mode 100644
index 00000000000..e3f1c95d66f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/mediaqueries/viewport-script-dynamic-ref.html
@@ -0,0 +1,9 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test Reference</title>
+<link rel="author" href="mailto:emilio@crisal.io">
+<meta name="viewport" content="width=300">
+<style>
+p { color: green; }
+</style>
+<p>Should be green</p>
diff --git a/tests/wpt/web-platform-tests/css/mediaqueries/viewport-script-dynamic.html b/tests/wpt/web-platform-tests/css/mediaqueries/viewport-script-dynamic.html
new file mode 100644
index 00000000000..7433877972b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/mediaqueries/viewport-script-dynamic.html
@@ -0,0 +1,20 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test: Meta viewport after a script and stylesheets</title>
+<link rel="author" href="mailto:emilio@crisal.io">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1424878">
+<link rel="help" href="https://drafts.csswg.org/mediaqueries/#mf-dimensions">
+<link rel="match" href="viewport-script-dynamic-ref.html">
+<style>
+p { color: green; }
+/* Ensure that we initially match it, and stop matching it afterwards */
+@media (min-width: 310px) {
+  p {
+    color: red;
+  }
+}
+</style>
+<!-- The broken script below is the point of the test, see the bugzilla bug. -->
+<script src="intentionally-broken-url.js"></script>
+<meta name="viewport" content="width=300">
+<p>Should be green</p>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-horiz-001v.xhtml b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-horiz-001v.xhtml
new file mode 100644
index 00000000000..f1dfdfdb86c
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-horiz-001v.xhtml
@@ -0,0 +1,73 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!-- Testcase with blocks as flex items in a horizontal flex container, with
+     various "flex" values and various combinations of the items
+     and with various writing-modes on the items. -->
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <title>
+      CSS Test: Testing flexbox layout algorithm property on block flex items in a horizontal flex container
+      (with various writing-modes on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com"/>
+    <link rel="help" href="http://www.w3.org/TR/css-flexbox-1/#layout-algorithm"/>
+    <link rel="match" href="flexbox-basic-block-horiz-001-ref.xhtml"/>
+    <style>
+      div { height: 100px; }
+      div.flexbox {
+        border: 1px dashed blue;
+        width: 200px;
+        font-size: 10px;
+        display: flex;
+      }
+      div.a {
+        flex: 1 0 30px;
+        background: lightgreen;
+        writing-mode: vertical-lr;
+      }
+      div.b {
+        flex: 2 0 20px;
+        background: yellow;
+        writing-mode: vertical-rl;
+      }
+      div.c {
+        flex: 3 0 40px;
+        background: orange;
+        writing-mode: sideways-lr;
+      }
+      div.flexNone {
+        flex: none;
+        background: pink;
+        writing-mode: vertical-lr;
+      }
+      div.flexBasis {
+        flex: 0 0 20px;
+        background: gray;
+        writing-mode: sideways-rl;
+      }
+      div.spacer {
+        width: 15px;
+        height: 15px;
+        background: purple;
+      }
+    </style>
+  </head>
+  <body>
+    <div class="flexbox"><div class="a"></div><div class="b"/></div>
+    <div class="flexbox"><div class="a"/><div class="c"/></div>
+    <div class="flexbox"><div class="a"/>
+      <div class="flexNone"><div class="spacer"/></div>
+    </div>
+    <div class="flexbox"><div class="b"/><div class="c"/></div>
+    <div class="flexbox"><div class="b"/>
+      <div class="flexNone"><div class="spacer"/><div class="spacer"/></div>
+    </div>
+
+    <div class="flexbox">
+      <div class="a"/><div class="b"/><div class="flexBasis"/><div class="c"/>
+    </div>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-vert-001v.xhtml b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-vert-001v.xhtml
new file mode 100644
index 00000000000..da943dfc56f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-block-vert-001v.xhtml
@@ -0,0 +1,75 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!-- Testcase with blocks as flex items in a vertical flex container, with
+     various "flex" values and various combinations of the items. -->
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <title>
+      CSS Test: Testing flexbox layout algorithm property on block flex items in a vertical flex container
+      (with various writing-modes on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com"/>
+    <link rel="help" href="http://www.w3.org/TR/css-flexbox-1/#layout-algorithm"/>
+    <link rel="match" href="flexbox-basic-block-vert-001-ref.xhtml"/>
+    <style>
+      div { width: 50px; }
+      div.flexbox {
+        float: left;
+        border: 1px dashed blue;
+        height: 200px;
+        font-size: 10px;
+        display: flex;
+        flex-direction: column;
+      }
+      div.a {
+        flex: 1 0 30px;
+        background: lightgreen;
+        writing-mode: vertical-lr;
+      }
+      div.b {
+        flex: 2 0 20px;
+        background: yellow;
+        writing-mode: vertical-rl;
+      }
+      div.c {
+        flex: 3 0 40px;
+        background: orange;
+        writing-mode: sideways-lr;
+      }
+      div.flexNone {
+        flex: none;
+        background: pink;
+        writing-mode: vertical-lr;
+      }
+      div.flexBasis {
+        flex: 0 0 20px;
+        background: gray;
+        writing-mode: sideways-rl;
+      }
+      div.spacer {
+        display: inline-block;
+        width: 15px;
+        height: 15px;
+        background: purple;
+      }
+    </style>
+  </head>
+  <body>
+    <div class="flexbox"><div class="a"></div><div class="b"/></div>
+    <div class="flexbox"><div class="a"/><div class="c"/></div>
+    <div class="flexbox"><div class="a"/>
+      <div class="flexNone"><div class="spacer"/></div>
+    </div>
+    <div class="flexbox"><div class="b"/><div class="c"/></div>
+    <div class="flexbox"><div class="b"/>
+      <div class="flexNone"><div class="spacer"/><div class="spacer"/></div>
+    </div>
+
+    <div class="flexbox">
+      <div class="a"/><div class="b"/><div class="flexBasis"/><div class="c"/>
+    </div>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-horiz-001v.xhtml b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-horiz-001v.xhtml
new file mode 100644
index 00000000000..ad623d77f7f
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-horiz-001v.xhtml
@@ -0,0 +1,105 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!--
+     This test checks that canvas elements behave correctly as flex items.
+-->
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <title>
+      CSS Test: Testing flexbox layout algorithm property on canvas flex items in a horizontal flex container
+      (with a vertical writing-mode on the canvas flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com"/>
+    <link rel="help" href="http://www.w3.org/TR/css-flexbox-1/#layout-algorithm"/>
+    <link rel="match" href="flexbox-basic-canvas-horiz-001-ref.xhtml"/>
+    <style>
+      div.flexbox {
+        width: 200px;
+        background: lightgreen;
+        display: flex;
+        justify-content: space-between;
+        margin-bottom: 5px;
+        line-height: 8px;
+      }
+      canvas {
+        min-width: 0;
+        width: 10px;
+        height: 20px;
+        border: 1px dotted green;
+        writing-mode: vertical-lr;
+      }
+    </style>
+  </head>
+  <body>
+
+    <!-- A) One flex item -->
+    <div class="flexbox">
+      <canvas/>
+    </div>
+
+    <!-- B) Text and a canvas (ensure they aren't merged into one flex item) -->
+    <div class="flexbox">
+      some words <canvas/>
+    </div>
+
+    <!-- C) Two canvas elements, getting stretched by different ratios, from 0.
+
+         Space-to-be-distributed = 200px - borders = 200 - (1 + 1) - (1 + 1)
+                                 = 196px
+
+         1st element gets 5/8 of space: 5/8 * 196px = 122.5px
+         1st element gets 3/8 of space: 3/8 * 196px = 73.5px
+      -->
+    <div class="flexbox">
+      <canvas style="flex: 5"/>
+      <canvas style="flex: 3"/>
+    </div>
+
+    <!-- D) Two canvas elements, getting stretched by different ratios, from
+         different flex bases.
+
+         Space-to-be-distributed = 200px - (33 + 1 + 1) - (13 + 1 + 1) = 150px
+         1st element gets 2/5 of space: 33px + 2/5 * 150px = 93px
+         1st element gets 3/5 of space: 13px + 3/5 * 150px = 103px
+      -->
+    <div class="flexbox">
+      <canvas style="width: 33px; flex: 2 auto"/>
+      <canvas style="width: 13px; flex: 3 auto"/>
+    </div>
+
+    <!-- E) Two flex items, getting shrunk by different amounts.
+
+         Space-to-be-distributed = 200px - (150 + 1 + 1) - (100 + 1 + 1) = -54px
+         First element scaled flex ratio = 4 * 150 = 600
+         Second element scaled flex ratio = 3 * 100 = 300
+           * So, total flexibility is 600 + 300 = 900
+
+         1st element gets 600/900 of space: 150 + 600/900 * -54 = 114px
+         2nd element gets 300/900 of space: 100 + 300/900 * -54 = 82px
+      -->
+    <div class="flexbox">
+      <canvas style="width: 150px; flex: 1 4 auto"/>
+      <canvas style="width: 100px; flex: 1 3 auto"/>
+    </div>
+
+    <!-- F) Making sure we don't grow past max-width -->
+    <!-- Same as (D), except we've added a max-width on the second element.
+      -->
+    <div class="flexbox">
+      <canvas style="width: 33px; flex: 2 auto"/>
+      <canvas style="width: 13px; max-width: 90px; flex: 3 auto"/>
+    </div>
+
+    <!-- G) Making sure we grow at least as large as min-width -->
+    <!-- Same as (C), except we've added a min-width on the second element.
+      -->
+    <div class="flexbox">
+      <canvas style="width: 33px; flex: 2 auto"/>
+      <canvas style="width: 13px; min-width: 150px; flex: 3 auto"/>
+    </div>
+
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-vert-001v.xhtml b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-vert-001v.xhtml
new file mode 100644
index 00000000000..057f63ae62b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-basic-canvas-vert-001v.xhtml
@@ -0,0 +1,107 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!--
+     This test checks that canvas elements behave correctly as flex items.
+-->
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <title>
+      CSS Test: Testing flexbox layout algorithm property on canvas flex items in a vertical flex container
+      (with a vertical writing-mode on the canvas flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com"/>
+    <link rel="help" href="http://www.w3.org/TR/css-flexbox-1/#layout-algorithm"/>
+    <link rel="match" href="flexbox-basic-canvas-vert-001-ref.xhtml"/>
+    <style>
+      div.flexbox {
+        height: 200px;
+        background: lightgreen;
+        display: flex;
+        justify-content: space-between;
+        flex-direction: column;
+        float: left;
+        margin-right: 10px;
+        font: 8px monospace;
+      }
+      canvas {
+        width: 20px;
+        height: 10px;
+        min-height: 0;
+        border: 1px dotted green;
+        writing-mode: vertical-lr;
+      }
+    </style>
+  </head>
+  <body>
+
+    <!-- A) One flex item -->
+    <div class="flexbox">
+      <canvas/>
+    </div>
+
+    <!-- B) Text and a canvas (ensure they aren't merged into one flex item) -->
+    <div class="flexbox">
+      a b <canvas/>
+    </div>
+
+    <!-- C) Two canvas elements, getting stretched by different ratios, from 0.
+
+         Space-to-be-distributed = 200px - borders = 200 - (1 + 1) - (1 + 1)
+                                 = 196px
+
+         1st element gets 5/8 of space: 5/8 * 196px = 122.5px
+         1st element gets 3/8 of space: 3/8 * 196px = 73.5px
+      -->
+    <div class="flexbox">
+      <canvas style="flex: 5"/>
+      <canvas style="flex: 3"/>
+    </div>
+
+    <!-- D) Two canvas elements, getting stretched by different ratios, from
+         different flex bases.
+
+         Space-to-be-distributed = 200px - (33 + 1 + 1) - (13 + 1 + 1) = 150px
+         1st element gets 2/5 of space: 33px + 2/5 * 150px = 93px
+         1st element gets 3/5 of space: 13px + 3/5 * 150px = 103px
+      -->
+    <div class="flexbox">
+      <canvas style="height: 33px; flex: 2 auto"/>
+      <canvas style="height: 13px; flex: 3 auto"/>
+    </div>
+
+    <!-- E) Two flex items, getting shrunk by different amounts.
+
+         Space-to-be-distributed = 200px - (150 + 1 + 1) - (100 + 1 + 1) = -54px
+         First element scaled flex ratio = 4 * 150 = 600
+         Second element scaled flex ratio = 3 * 100 = 300
+           * So, total flexibility is 600 + 300 = 900
+
+         1st element gets 600/900 of space: 150 + 600/900 * -54 = 114px
+         2nd element gets 300/900 of space: 100 + 300/900 * -54 = 82px
+      -->
+    <div class="flexbox">
+      <canvas style="height: 150px; flex: 1 4 auto"/>
+      <canvas style="height: 100px; flex: 1 3 auto"/>
+    </div>
+
+    <!-- F) Making sure we don't grow past max-height -->
+    <!-- Same as (D), except we've added a max-height on the second element.
+      -->
+    <div class="flexbox">
+      <canvas style="height: 33px; flex: 2 auto"/>
+      <canvas style="height: 13px; max-height: 90px; flex: 3 auto"/>
+    </div>
+
+    <!-- G) Making sure we grow at least as large as min-height -->
+    <!-- Same as (C), except we've added a min-height on the second element.
+      -->
+    <div class="flexbox">
+      <canvas style="height: 33px; flex: 2 auto"/>
+      <canvas style="height: 13px; min-height: 150px; flex: 3 auto"/>
+    </div>
+
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-001v.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-001v.html
new file mode 100644
index 00000000000..4cc910b9e28
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-001v.html
@@ -0,0 +1,128 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>
+      CSS Test: Testing how explicit main-size & cross-size constraints
+      influence sizing on non-stretched flex item w/ intrinsic ratio
+      (with a vertical writing-mode on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-main-size">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-cross-size">
+    <link rel="match" href="flexbox-intrinsic-ratio-001-ref.html">
+    <style>
+      .flexbox {
+        display: flex;
+        flex-direction: row;
+        border: 1px solid black;
+        margin: 0 2px 2px 0; /* (Just for spacing things out, visually) */
+        width: 40px;
+        height: 40px;
+
+        justify-content: flex-start;
+        align-items: flex-start;
+
+        float: left; /* For testing in "rows" */
+      }
+      br { clear: both; }
+
+      .flexbox > * {
+        writing-mode: vertical-lr;
+
+        /* Disable "min-width:auto"/"min-height:auto" to focus purely on
+           later channels of influence. */
+        min-width: 0;
+        min-height: 0;
+      }
+    </style>
+  </head>
+  <body>
+    <!-- NOTE: solidblue.png has an intrinsic size of 16px by 16px. -->
+
+    <!-- Row 1: no special sizing: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png">
+    </div>
+    <br>
+
+    <!-- Row 2: Specified main-size, cross-size, or flex-basis: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="flex: 0 0 30px">
+    </div>
+    <br>
+
+    <!-- Row 3: min main-size OR min cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 4: max main-size OR max cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              max-height: 6px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 6px;
+                                              max-height: 10px">
+    </div>
+    <br>
+
+    <!-- Row 5: min main-size vs. max cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 6: min|max main-size vs. explicit cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 10px;
+                                              min-height: 30px">
+    </div>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-002v.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-002v.html
new file mode 100644
index 00000000000..0df92f9954c
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-002v.html
@@ -0,0 +1,128 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>
+      CSS Test: Testing how explicit main-size & cross-size constraints
+      influence sizing on non-stretched flex item w/ intrinsic ratio
+      (with a vertical writing-mode on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-main-size">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-cross-size">
+    <link rel="match" href="flexbox-intrinsic-ratio-001-ref.html">
+    <style>
+      .flexbox {
+        display: flex;
+        flex-direction: column;
+        border: 1px solid black;
+        margin: 0 2px 2px 0; /* (Just for spacing things out, visually) */
+        width: 40px;
+        height: 40px;
+
+        justify-content: flex-start;
+        align-items: flex-start;
+
+        float: left; /* For testing in "rows" */
+      }
+      br { clear: both; }
+
+      .flexbox > * {
+        writing-mode: vertical-lr;
+
+        /* Disable "min-width:auto"/"min-height:auto" to focus purely on
+           later channels of influence. */
+        min-width: 0;
+        min-height: 0;
+      }
+    </style>
+  </head>
+  <body>
+    <!-- NOTE: solidblue.png has an intrinsic size of 16px by 16px. -->
+
+    <!-- Row 1: no special sizing: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png">
+    </div>
+    <br>
+
+    <!-- Row 2: Specified main-size, cross-size, or flex-basis: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="flex: 0 0 30px">
+    </div>
+    <br>
+
+    <!-- Row 3: min main-size OR min cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 4: max main-size OR max cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              max-height: 6px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 6px;
+                                              max-height: 10px">
+    </div>
+    <br>
+
+    <!-- Row 5: min main-size vs. max cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 6: min|max main-size vs. explicit cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 10px;
+                                              min-height: 30px">
+    </div>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-003v.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-003v.html
new file mode 100644
index 00000000000..cb9275fd8cf
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-003v.html
@@ -0,0 +1,128 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>
+      CSS Test: Testing how explicit main-size & cross-size constraints
+      influence sizing on stretched flex item w/ intrinsic ratio
+      (with a vertical writing-mode on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-main-size">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-cross-size">
+    <link rel="match" href="flexbox-intrinsic-ratio-003-ref.html">
+    <style>
+      .flexbox {
+        display: flex;
+        flex-direction: row;
+        border: 1px solid black;
+        margin: 0 2px 2px 0; /* (Just for spacing things out, visually) */
+        width: 40px;
+        height: 40px;
+
+        justify-content: flex-start;
+        align-items: stretch;
+
+        float: left; /* For testing in "rows" */
+      }
+      br { clear: both; }
+
+      .flexbox > * {
+        writing-mode: vertical-rl;
+
+        /* Disable "min-width:auto"/"min-height:auto" to focus purely on
+           later channels of influence. */
+        min-width: 0;
+        min-height: 0;
+      }
+    </style>
+  </head>
+  <body>
+    <!-- NOTE: solidblue.png has an intrinsic size of 16px by 16px. -->
+
+    <!-- Row 1: no special sizing: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png">
+    </div>
+    <br>
+
+    <!-- Row 2: Specified main-size, cross-size, or flex-basis: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="flex: 0 0 30px">
+    </div>
+    <br>
+
+    <!-- Row 3: min main-size OR min cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 4: max main-size OR max cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              max-height: 6px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 6px;
+                                              max-height: 10px">
+    </div>
+    <br>
+
+    <!-- Row 5: min main-size vs. max cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 6: min|max main-size vs. explicit cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 10px;
+                                              min-height: 30px">
+    </div>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-004v.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-004v.html
new file mode 100644
index 00000000000..01c5271c455
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-004v.html
@@ -0,0 +1,128 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>
+      CSS Test: Testing how explicit main-size & cross-size constraints
+      influence sizing on stretched flex item w/ intrinsic ratio
+      (with a vertical writing-mode on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-main-size">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-cross-size">
+    <link rel="match" href="flexbox-intrinsic-ratio-004-ref.html">
+    <style>
+      .flexbox {
+        display: flex;
+        flex-direction: column;
+        border: 1px solid black;
+        margin: 0 2px 2px 0; /* (Just for spacing things out, visually) */
+        width: 40px;
+        height: 40px;
+
+        justify-content: flex-start;
+        align-items: stretch;
+
+        float: left; /* For testing in "rows" */
+      }
+      br { clear: both; }
+
+      .flexbox > * {
+        writing-mode: vertical-rl;
+
+        /* Disable "min-width:auto"/"min-height:auto" to focus purely on
+           later channels of influence. */
+        min-width: 0;
+        min-height: 0;
+      }
+    </style>
+  </head>
+  <body>
+    <!-- NOTE: solidblue.png has an intrinsic size of 16px by 16px. -->
+
+    <!-- Row 1: no special sizing: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png">
+    </div>
+    <br>
+
+    <!-- Row 2: Specified main-size, cross-size, or flex-basis: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="flex: 0 0 30px">
+    </div>
+    <br>
+
+    <!-- Row 3: min main-size OR min cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 4: max main-size OR max cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              max-height: 6px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 6px;
+                                              max-height: 10px">
+    </div>
+    <br>
+
+    <!-- Row 5: min main-size vs. max cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 6: min|max main-size vs. explicit cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 10px;
+                                              min-height: 30px">
+    </div>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-005v.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-005v.html
new file mode 100644
index 00000000000..ed1dcace0f3
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-005v.html
@@ -0,0 +1,129 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>
+      CSS Test: Testing how explicit main-size & cross-size constraints
+      influence sizing on non-stretched flexible flex item w/ intrinsic ratio
+      (with a vertical writing-mode on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-main-size">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-cross-size">
+    <link rel="match" href="flexbox-intrinsic-ratio-005-ref.html">
+    <style>
+      .flexbox {
+        display: flex;
+        flex-direction: row;
+        border: 1px solid black;
+        margin: 0 2px 2px 0; /* (Just for spacing things out, visually) */
+        width: 40px;
+        height: 40px;
+
+        justify-content: flex-start;
+        align-items: flex-start;
+
+        float: left; /* For testing in "rows" */
+      }
+      br { clear: both; }
+
+      .flexbox > * {
+        flex: 1;
+        writing-mode: vertical-lr;
+
+        /* Disable "min-width:auto"/"min-height:auto" to focus purely on
+           later channels of influence. */
+        min-width: 0;
+        min-height: 0;
+      }
+    </style>
+  </head>
+  <body>
+    <!-- NOTE: solidblue.png has an intrinsic size of 16px by 16px. -->
+
+    <!-- Row 1: no special sizing: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png">
+    </div>
+    <br>
+
+    <!-- Row 2: Specified main-size, cross-size, or flex-basis: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="flex: 1 1 30px">
+    </div>
+    <br>
+
+    <!-- Row 3: min main-size OR min cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 4: max main-size OR max cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              max-height: 6px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 6px;
+                                              max-height: 10px">
+    </div>
+    <br>
+
+    <!-- Row 5: min main-size vs. max cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 6: min|max main-size vs. explicit cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 10px;
+                                              min-height: 30px">
+    </div>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-006v.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-006v.html
new file mode 100644
index 00000000000..8c12fad8c79
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-intrinsic-ratio-006v.html
@@ -0,0 +1,129 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>
+      CSS Test: Testing how explicit main-size & cross-size constraints
+      influence sizing on non-stretched flexible flex item w/ intrinsic ratio
+      (with a vertical writing-mode on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-main-size">
+    <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#hypothetical-cross-size">
+    <link rel="match" href="flexbox-intrinsic-ratio-006-ref.html">
+    <style>
+      .flexbox {
+        display: flex;
+        flex-direction: column;
+        border: 1px solid black;
+        margin: 0 2px 2px 0; /* (Just for spacing things out, visually) */
+        width: 40px;
+        height: 40px;
+
+        justify-content: flex-start;
+        align-items: flex-start;
+
+        float: left; /* For testing in "rows" */
+      }
+      br { clear: both; }
+
+      .flexbox > * {
+        flex: 1;
+        writing-mode: vertical-lr;
+
+        /* Disable "min-width:auto"/"min-height:auto" to focus purely on
+           later channels of influence. */
+        min-width: 0;
+        min-height: 0;
+      }
+    </style>
+  </head>
+  <body>
+    <!-- NOTE: solidblue.png has an intrinsic size of 16px by 16px. -->
+
+    <!-- Row 1: no special sizing: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png">
+    </div>
+    <br>
+
+    <!-- Row 2: Specified main-size, cross-size, or flex-basis: -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="flex: 1 1 30px">
+    </div>
+    <br>
+
+    <!-- Row 3: min main-size OR min cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              min-height: 34px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 34px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 4: max main-size OR max cross-size, or both -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              max-height: 6px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 6px;
+                                              max-height: 10px">
+    </div>
+    <br>
+
+    <!-- Row 5: min main-size vs. max cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              min-height: 30px">
+    </div>
+    <br>
+
+    <!-- Row 6: min|max main-size vs. explicit cross-size, & vice versa -->
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="min-width: 30px;
+                                              height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 30px;
+                                              max-height: 10px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="max-width: 10px;
+                                              height: 30px">
+    </div>
+    <div class="flexbox">
+      <img src="support/solidblue.png" style="width: 10px;
+                                              min-height: 30px">
+    </div>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-002v.xhtml b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-002v.xhtml
new file mode 100644
index 00000000000..a02e3406c90
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-002v.xhtml
@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!-- Testcase with margin/border/padding on flex items
+     and with various writing-modes on the items. -->
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <title>
+      CSS Test: Testing margins, borders, and padding on flex items in a horizontal flex container
+      (with a vertical writing-mode on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com"/>
+    <link rel="help" href="http://www.w3.org/TR/css-flexbox-1/#layout-algorithm"/>
+    <link rel="match" href="flexbox-mbp-horiz-002-ref.xhtml"/>
+    <style>
+      div { height: 100px; border: 0; }
+      div.flexbox {
+        width: 200px;
+        font-size: 10px;
+        display: flex;
+      }
+      div.a {
+        flex: 1 0 9px;
+        background: lightgreen;
+        margin-left: 1px;
+        margin-right: 3px;
+        border-style: dotted;
+        border-left-width: 2px;
+        border-right-width: 4px;
+        padding-left: 5px;
+        padding-right: 6px;
+        writing-mode: vertical-lr;
+      }
+      div.b {
+        flex: 2 0 1px;
+        background: yellow;
+        margin-left: 2px;
+        margin-right: 4px;
+        border-style: dashed;
+        border-left-width: 7px;
+        border-right-width: 3px;
+        padding-left: 1px;
+        padding-right: 2px;
+        writing-mode: vertical-rl;
+      }
+      div.c {
+        flex: 3 0 40px;
+        background: orange;
+        writing-mode: sideways-lr;
+      }
+      div.flexNone {
+        flex: none;
+        background: pink;
+        writing-mode: vertical-lr;
+      }
+      div.flexBasis {
+        flex: 0 0 20px;
+        background: gray;
+        writing-mode: sideways-rl;
+      }
+      div.spacer {
+        width: 15px;
+        height: 15px;
+        background: purple;
+      }
+    </style>
+  </head>
+  <body>
+    <div class="flexbox"><div class="a"></div><div class="b"/></div>
+    <div class="flexbox"><div class="a"/><div class="c"/></div>
+    <div class="flexbox"><div class="a"/>
+      <div class="flexNone"><div class="spacer"/></div>
+    </div>
+    <div class="flexbox"><div class="b"/><div class="c"/></div>
+    <div class="flexbox"><div class="b"/>
+      <div class="flexNone"><div class="spacer"/><div class="spacer"/></div>
+    </div>
+
+    <div class="flexbox">
+      <div class="a"/><div class="b"/><div class="flexBasis"/><div class="c"/>
+    </div>
+  </body>
+</html>
+
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-003v.xhtml b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-003v.xhtml
new file mode 100644
index 00000000000..8baef302272
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-mbp-horiz-003v.xhtml
@@ -0,0 +1,88 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!-- Testcase with border/padding on a flex container and on its children -->
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <title>
+      CSS Test: Testing borders and padding on a horizontal flex container and its flex items
+      (with a vertical writing-mode on the flex items).
+    </title>
+    <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com"/>
+    <link rel="help" href="http://www.w3.org/TR/css-flexbox-1/#layout-algorithm"/>
+    <link rel="match" href="flexbox-mbp-horiz-003-ref.xhtml"/>
+    <style>
+      div { height: 20px; border: 0; }
+      div.flexbox {
+        width: 200px;
+        display: flex;
+        margin-bottom: 2px;
+      }
+
+      <!-- customizations for flex container border/padding -->
+      .borderA {
+        border-style: dashed;
+        border-color: purple;
+        border-top-width: 6px;
+        border-right-width: 4px;
+        border-bottom-width: 2px;
+        border-left-width: 8px;
+      }
+
+      .borderB {
+        border-style: dashed;
+        border-color: purple;
+        border-top-width: 4px;
+        border-right-width: 5px;
+        border-bottom-width: 6px;
+        border-left-width: 7px;
+      }
+
+      .paddingA {
+        padding: 4px 3px 2px 1px;
+      }
+
+      .paddingB {
+        padding: 8px 11px 14px 17px;
+      }
+
+      div.child1 {
+        flex: 1 0 24px;
+        background: lightgreen;
+        border-style: dotted;
+        border-left-width: 2px;
+        border-right-width: 4px;
+        writing-mode: vertical-rl;
+      }
+      div.child2 {
+        flex: 2 0 10px;
+        background: yellow;
+        border-style: dashed;
+        border-left-width: 7px;
+        border-right-width: 3px;
+        writing-mode: vertical-lr;
+      }
+    </style>
+  </head>
+  <body>
+    <div class="flexbox borderA"
+         ><div class="child1"/><div class="child2"/></div>
+    <div class="flexbox borderA paddingA"
+         ><div class="child1"/><div class="child2"/></div>
+    <div class="flexbox borderA paddingB"
+         ><div class="child1"/><div class="child2"/></div>
+    <div class="flexbox borderB"
+         ><div class="child1"/><div class="child2"/></div>
+    <div class="flexbox borderB paddingA"
+         ><div class="child1"/><div class="child2"/></div>
+    <div class="flexbox borderB paddingB"
+         ><div class="child1"/><div class="child2"/></div>
+    <div class="flexbox paddingA"
+         ><div class="child1"/><div class="child2"/></div>
+    <div class="flexbox paddingB"
+         ><div class="child1"/><div class="child2"/></div>
+  </body>
+</html>
+
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010-ref.html
new file mode 100644
index 00000000000..e4884164123
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010-ref.html
@@ -0,0 +1,94 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: block;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 150px;
+    width: 500px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+
+  .container > .hl, .container > .hr {
+    /* In the testcase, these items are stretched vertically
+       via the default "align-self:stretch" behavior, and because
+       they have a height of "auto".
+       (The rest of the items have a non-auto height from "inline-size"
+       and their vertical writing-mode, so those ones do not stretch.) */
+    height: 118px;
+  }
+
+  .container.hl > * { float: left; }
+  .container.hr > * { float: right; }
+
+  </style>
+</head>
+<body>
+
+<div class="container hl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container hl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+<div class="container hr">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container hr">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010.html
new file mode 100644
index 00000000000..55c50e850f4
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-010.html
@@ -0,0 +1,88 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>
+    CSS Test: Testing a mix of flex items with various values for
+    'writing-mode' / 'direction' in a horizontal row-oriented flex container.
+  </title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#flex-direction-property">
+  <link rel="help" href="https://www.w3.org/TR/css-writing-modes-3/#propdef-writing-mode">
+  <link rel="match" href="flexbox-writing-mode-010-ref.html">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: flex;
+    flex-direction: row;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 150px;
+    width: 500px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+  </style>
+</head>
+<body>
+
+<div class="container hl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container hl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+<div class="container hr">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container hr">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011-ref.html
new file mode 100644
index 00000000000..8b926490b63
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011-ref.html
@@ -0,0 +1,97 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: block;
+    float: left;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 500px;
+    width: 150px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+
+    /* This really floats to top ('logical left'), since all the containers
+       have a vertical writing mode. */
+    float: left;
+  }
+
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+
+
+  .container > .vl,     .container > .vr,
+  .container > .vl_rtl, .container > .vr_rtl {
+    /* In the testcase, these items are stretched horizontally
+       via the default "align-self:stretch" behavior, and because
+       they have a width of "auto".
+       (The rest of the items have a non-auto width from "inline-size"
+       and their horizontal writing-mode, so those ones do not stretch.) */
+    width: 126px;
+  }
+  </style>
+</head>
+<body>
+
+<div class="container vl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+<div class="container vr">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vr">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011.html
new file mode 100644
index 00000000000..6114e192758
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-011.html
@@ -0,0 +1,89 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>
+    CSS Test: Testing a mix of flex items with various values for
+    'writing-mode' / 'direction' in a vertical row-oriented flex container.
+  </title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#flex-direction-property">
+  <link rel="help" href="https://www.w3.org/TR/css-writing-modes-3/#propdef-writing-mode">
+  <link rel="match" href="flexbox-writing-mode-011-ref.html">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: flex;
+    flex-direction: row;
+    float: left;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 500px;
+    width: 150px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+  </style>
+</head>
+<body>
+
+<div class="container vl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+<div class="container vr">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vr">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012-ref.html
new file mode 100644
index 00000000000..c03358be423
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012-ref.html
@@ -0,0 +1,97 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: block;
+    float: left;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 500px;
+    width: 150px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+
+    /* This really floats to top ('logical left'), since all the containers
+       have a vertical writing mode. */
+    float: right;
+  }
+
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+
+
+  .container > .vl,     .container > .vr,
+  .container > .vl_rtl, .container > .vr_rtl {
+    /* In the testcase, these items are stretched horizontally
+       via the default "align-self:stretch" behavior, and because
+       they have a width of "auto".
+       (The rest of the items have a non-auto width from "inline-size"
+       and their horizontal writing-mode, so those ones do not stretch.) */
+    width: 126px;
+  }
+  </style>
+</head>
+<body>
+
+<div class="container vl_rtl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vl_rtl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+<div class="container vr_rtl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vr_rtl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012.html
new file mode 100644
index 00000000000..a7b05f178dd
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-012.html
@@ -0,0 +1,90 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>
+    CSS Test: Testing a mix of flex items with various values for
+    'writing-mode' / 'direction' in a vertical row-oriented flex container
+    with 'direction' flipped.
+  </title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#flex-direction-property">
+  <link rel="help" href="https://www.w3.org/TR/css-writing-modes-3/#propdef-writing-mode">
+  <link rel="match" href="flexbox-writing-mode-012-ref.html">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: flex;
+    flex-direction: row;
+    float: left;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 500px;
+    width: 150px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+  </style>
+</head>
+<body>
+
+<div class="container vl_rtl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vl_rtl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+<div class="container vr_rtl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vr_rtl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013-ref.html
new file mode 100644
index 00000000000..2a27003a5ce
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013-ref.html
@@ -0,0 +1,98 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: block;
+    float: left;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 500px;
+    width: 150px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  nocollapse {
+    /* special element to disable margin-collapsing */
+    display: block;
+    overflow: hidden;
+    height: 0;
+  }
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+
+  .container > .vl,     .container > .vr,
+  .container > .vl_rtl, .container > .vr_rtl {
+    /* In the testcase, these items are stretched horizontally
+       via the default "align-self:stretch" behavior, and because
+       they have a width of "auto".
+       (The rest of the items have a non-auto width from "inline-size"
+       and their horizontal writing-mode, so those ones do not stretch.) */
+    width: 126px;
+  }
+  </style>
+</head>
+<body>
+
+<div class="container hl">
+  <span class="hl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hl big">d e</span>        <nocollapse></nocollapse>
+  <span class="hr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vl big">d e</span>        <nocollapse></nocollapse>
+</div>
+<div class="container hl">
+  <span class="vr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vl_rtl big">d e</span>    <nocollapse></nocollapse>
+  <span class="vr_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vr_rtl big">d e</span>    <nocollapse></nocollapse>
+</div>
+<div class="container hr">
+  <span class="hl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hl big">d e</span>        <nocollapse></nocollapse>
+  <span class="hr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vl big">d e</span>        <nocollapse></nocollapse>
+</div>
+<div class="container hr">
+  <span class="vr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vl_rtl big">d e</span>    <nocollapse></nocollapse>
+  <span class="vr_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vr_rtl big">d e</span>    <nocollapse></nocollapse>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013.html
new file mode 100644
index 00000000000..a5d483c4429
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-013.html
@@ -0,0 +1,89 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>
+    CSS Test: Testing a mix of flex items with various values for
+    'writing-mode' / 'direction' in a horizontal column-oriented flex container.
+  </title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#flex-direction-property">
+  <link rel="help" href="https://www.w3.org/TR/css-writing-modes-3/#propdef-writing-mode">
+  <link rel="match" href="flexbox-writing-mode-013-ref.html">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: flex;
+    flex-direction: column;
+    float: left;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 500px;
+    width: 150px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+  </style>
+</head>
+<body>
+
+<div class="container hl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container hl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+<div class="container hr">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container hr">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014-ref.html
new file mode 100644
index 00000000000..4e4f5904a16
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014-ref.html
@@ -0,0 +1,96 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: block;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 150px;
+    width: 500px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  nocollapse {
+    /* special element to disable margin-collapsing */
+    display: block;
+    overflow: hidden;
+    height: 0;
+  }
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+
+  .container > .hl, .container > .hr {
+    /* In the testcase, these items are stretched vertically
+       via the default "align-self:stretch" behavior, and because
+       they have a height of "auto".
+       (The rest of the items have a non-auto height from "inline-size"
+       and their vertical writing-mode, so those ones do not stretch.) */
+    height: 118px;
+  }
+  </style>
+</head>
+<body>
+
+<div class="container vl">
+  <span class="hl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hl big">d e</span>        <nocollapse></nocollapse>
+  <span class="hr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vl big">d e</span>        <nocollapse></nocollapse>
+</div>
+<div class="container vl">
+  <span class="vr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vl_rtl big">d e</span>    <nocollapse></nocollapse>
+  <span class="vr_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vr_rtl big">d e</span>    <nocollapse></nocollapse>
+</div>
+<div class="container vr">
+  <span class="hl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hl big">d e</span>        <nocollapse></nocollapse>
+  <span class="hr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vl big">d e</span>        <nocollapse></nocollapse>
+</div>
+<div class="container vr">
+  <span class="vr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vl_rtl big">d e</span>    <nocollapse></nocollapse>
+  <span class="vr_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vr_rtl big">d e</span>    <nocollapse></nocollapse>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014.html
new file mode 100644
index 00000000000..1a5443279a4
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-014.html
@@ -0,0 +1,88 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>
+    CSS Test: Testing a mix of flex items with various values for
+    'writing-mode' / 'direction' in a vertical column-oriented flex container.
+  </title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#flex-direction-property">
+  <link rel="help" href="https://www.w3.org/TR/css-writing-modes-3/#propdef-writing-mode">
+  <link rel="match" href="flexbox-writing-mode-014-ref.html">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: flex;
+    flex-direction: column;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 150px;
+    width: 500px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+  </style>
+</head>
+<body>
+
+<div class="container vl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+<div class="container vr">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vr">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015-ref.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015-ref.html
new file mode 100644
index 00000000000..a236ca11d53
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015-ref.html
@@ -0,0 +1,96 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: block;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 150px;
+    width: 500px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  nocollapse {
+    /* special element to disable margin-collapsing */
+    display: block;
+    overflow: hidden;
+    height: 0;
+  }
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+
+  .container > .hl, .container > .hr {
+    /* In the testcase, these items are stretched vertically
+       via the default "align-self:stretch" behavior, and because
+       they have a height of "auto".
+       (The rest of the items have a non-auto height from "inline-size"
+       and their vertical writing-mode, so those ones do not stretch.) */
+    height: 118px;
+  }
+  </style>
+</head>
+<body>
+
+<div class="container vl_rtl">
+  <span class="hl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hl big">d e</span>        <nocollapse></nocollapse>
+  <span class="hr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vl big">d e</span>        <nocollapse></nocollapse>
+</div>
+<div class="container vl_rtl">
+  <span class="vr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vl_rtl big">d e</span>    <nocollapse></nocollapse>
+  <span class="vr_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vr_rtl big">d e</span>    <nocollapse></nocollapse>
+</div>
+<div class="container vr_rtl">
+  <span class="hl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hl big">d e</span>        <nocollapse></nocollapse>
+  <span class="hr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="hr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vl big">d e</span>        <nocollapse></nocollapse>
+</div>
+<div class="container vr_rtl">
+  <span class="vr small">a b c</span>    <nocollapse></nocollapse>
+  <span class="vr big">d e</span>        <nocollapse></nocollapse>
+  <span class="vl_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vl_rtl big">d e</span>    <nocollapse></nocollapse>
+  <span class="vr_rtl small">a b c</span><nocollapse></nocollapse>
+  <span class="vr_rtl big">d e</span>    <nocollapse></nocollapse>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015.html b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015.html
new file mode 100644
index 00000000000..af1f9b84567
--- /dev/null
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-writing-mode-015.html
@@ -0,0 +1,89 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>
+    CSS Test: Testing a mix of flex items with various values for
+    'writing-mode' / 'direction' in a vertical column-oriented flex container
+    with 'direction' flipped.
+  </title>
+  <meta charset="utf-8">
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="https://www.w3.org/TR/css-flexbox-1/#flex-direction-property">
+  <link rel="help" href="https://www.w3.org/TR/css-writing-modes-3/#propdef-writing-mode">
+  <link rel="match" href="flexbox-writing-mode-015-ref.html">
+  <link rel="stylesheet" type="text/css" href="support/ahem.css">
+  <style>
+  .container {
+    display: flex;
+    flex-direction: column;
+    border: 2px solid purple;
+    padding: 2px;
+    margin-bottom: 2em;
+    height: 150px;
+    width: 500px;
+  }
+
+  span {
+    display: block;
+    background: lightgrey;
+    border: 2px solid black;
+    /* If browser supports it, signal the inline direction with border color: */
+    border-block-start-color: orange;
+    border-inline-start-color: lime;
+
+    margin: 11px 13px 17px 7px;
+    inline-size: 6px;
+  }
+
+  .small { font: 12px Ahem; }
+  .big   { font: 20px Ahem; }
+
+  .hl  { writing-mode: horizontal-tb;  direction: ltr; }
+  .hr  { writing-mode: horizontal-tb;  direction: rtl; }
+  .vl  { writing-mode: vertical-lr;    direction: ltr; }
+  .vr  { writing-mode: vertical-rl;    direction: ltr; }
+  .vl_rtl { writing-mode: vertical-lr; direction: rtl; }
+  .vr_rtl { writing-mode: vertical-rl; direction: rtl; }
+  </style>
+</head>
+<body>
+
+<div class="container vl_rtl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vl_rtl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+<div class="container vr_rtl">
+  <span class="hl small">a b c</span>
+  <span class="hl big">d e</span>
+  <span class="hr small">a b c</span>
+  <span class="hr big">d e</span>
+  <span class="vl small">a b c</span>
+  <span class="vl big">d e</span>
+</div>
+<div class="container vr_rtl">
+  <span class="vr small">a b c</span>
+  <span class="vr big">d e</span>
+  <span class="vl_rtl small">a b c</span>
+  <span class="vl_rtl big">d e</span>
+  <span class="vr_rtl small">a b c</span>
+  <span class="vr_rtl big">d e</span>
+</div>
+
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/reftest.list b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/reftest.list
index cb4c09e4fc9..d9252b29343 100644
--- a/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/reftest.list
+++ b/tests/wpt/web-platform-tests/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/reftest.list
@@ -61,11 +61,15 @@
 
 # Basic tests with with blocks as flex items
 == flexbox-basic-block-horiz-001.xhtml flexbox-basic-block-horiz-001-ref.xhtml
+== flexbox-basic-block-horiz-001v.xhtml flexbox-basic-block-horiz-001-ref.xhtml
 == flexbox-basic-block-vert-001.xhtml flexbox-basic-block-vert-001-ref.xhtml
+== flexbox-basic-block-vert-001v.xhtml flexbox-basic-block-vert-001-ref.xhtml
 
 # Tests for basic handling of <canvas>/<img>/etc as a flex item
 == flexbox-basic-canvas-horiz-001.xhtml   flexbox-basic-canvas-horiz-001-ref.xhtml
+== flexbox-basic-canvas-horiz-001v.xhtml  flexbox-basic-canvas-horiz-001-ref.xhtml
 == flexbox-basic-canvas-vert-001.xhtml    flexbox-basic-canvas-vert-001-ref.xhtml
+== flexbox-basic-canvas-vert-001v.xhtml   flexbox-basic-canvas-vert-001-ref.xhtml
 == flexbox-basic-fieldset-horiz-001.xhtml flexbox-basic-fieldset-horiz-001-ref.xhtml
 == flexbox-basic-fieldset-vert-001.xhtml  flexbox-basic-fieldset-vert-001-ref.xhtml
 == flexbox-basic-iframe-horiz-001.xhtml   flexbox-basic-iframe-horiz-001-ref.xhtml
@@ -107,11 +111,17 @@
 # (Note that tests 001 and 002 share a reference case; they render the same,
 # because they don't do any direction-specific stretching/flexing.)
 == flexbox-intrinsic-ratio-001.html flexbox-intrinsic-ratio-001-ref.html
+== flexbox-intrinsic-ratio-001v.html flexbox-intrinsic-ratio-001-ref.html
 == flexbox-intrinsic-ratio-002.html flexbox-intrinsic-ratio-001-ref.html
+== flexbox-intrinsic-ratio-002v.html flexbox-intrinsic-ratio-001-ref.html
 == flexbox-intrinsic-ratio-003.html flexbox-intrinsic-ratio-003-ref.html
+== flexbox-intrinsic-ratio-003v.html flexbox-intrinsic-ratio-003-ref.html
 == flexbox-intrinsic-ratio-004.html flexbox-intrinsic-ratio-004-ref.html
+== flexbox-intrinsic-ratio-004v.html flexbox-intrinsic-ratio-004-ref.html
 == flexbox-intrinsic-ratio-005.html flexbox-intrinsic-ratio-005-ref.html
+== flexbox-intrinsic-ratio-005v.html flexbox-intrinsic-ratio-005-ref.html
 == flexbox-intrinsic-ratio-006.html flexbox-intrinsic-ratio-006-ref.html
+== flexbox-intrinsic-ratio-006v.html flexbox-intrinsic-ratio-006-ref.html
 
 # Tests for flex items as (pseudo) stacking contexts
 == flexbox-items-as-stacking-contexts-001.xhtml flexbox-items-as-stacking-contexts-001-ref.xhtml
@@ -141,7 +151,9 @@
 == flexbox-mbp-horiz-001-rtl-reverse.xhtml flexbox-mbp-horiz-001-ref.xhtml
 == flexbox-mbp-horiz-002a.xhtml            flexbox-mbp-horiz-002-ref.xhtml
 == flexbox-mbp-horiz-002b.xhtml            flexbox-mbp-horiz-002-ref.xhtml
+== flexbox-mbp-horiz-002v.xhtml            flexbox-mbp-horiz-002-ref.xhtml
 == flexbox-mbp-horiz-003.xhtml             flexbox-mbp-horiz-003-ref.xhtml
+== flexbox-mbp-horiz-003v.xhtml            flexbox-mbp-horiz-003-ref.xhtml
 == flexbox-mbp-horiz-003-reverse.xhtml     flexbox-mbp-horiz-003-reverse-ref.xhtml
 == flexbox-mbp-horiz-004.xhtml             flexbox-mbp-horiz-004-ref.xhtml
 
@@ -199,7 +211,8 @@
 == flexbox-with-pseudo-elements-002.html flexbox-with-pseudo-elements-002-ref.html
 == flexbox-with-pseudo-elements-003.html flexbox-with-pseudo-elements-003-ref.html
 
-# Tests for combined influence of 'writing-mode' & 'direction' on flex axes
+# Tests for combined influence of 'writing-mode' & 'direction'
+# on flex container axes & flex item placement
 == flexbox-writing-mode-001.html flexbox-writing-mode-001-ref.html
 == flexbox-writing-mode-002.html flexbox-writing-mode-002-ref.html
 == flexbox-writing-mode-003.html flexbox-writing-mode-003-ref.html
@@ -209,6 +222,12 @@
 == flexbox-writing-mode-007.html flexbox-writing-mode-007-ref.html
 == flexbox-writing-mode-008.html flexbox-writing-mode-008-ref.html
 == flexbox-writing-mode-009.html flexbox-writing-mode-009-ref.html
+== flexbox-writing-mode-010.html flexbox-writing-mode-010-ref.html
+== flexbox-writing-mode-011.html flexbox-writing-mode-011-ref.html
+== flexbox-writing-mode-012.html flexbox-writing-mode-012-ref.html
+== flexbox-writing-mode-013.html flexbox-writing-mode-013-ref.html
+== flexbox-writing-mode-014.html flexbox-writing-mode-014-ref.html
+== flexbox-writing-mode-015.html flexbox-writing-mode-015-ref.html
 
 # Single-line size clamping
 == flexbox-single-line-clamp-1.html flexbox-single-line-clamp-1-ref.html
diff --git a/tests/wpt/web-platform-tests/custom-elements/Document-createElement.html b/tests/wpt/web-platform-tests/custom-elements/Document-createElement.html
index 97a56595502..21f024c5735 100644
--- a/tests/wpt/web-platform-tests/custom-elements/Document-createElement.html
+++ b/tests/wpt/web-platform-tests/custom-elements/Document-createElement.html
@@ -36,12 +36,18 @@ test(function () {
     customElements.define('autonomous-custom-element', AutonomousCustomElement);
     customElements.define('is-custom-element', IsCustomElement);
 
-    var instance = document.createElement('autonomous-custom-element', { is: "is-custom-element"});
+    var instance = document.createElement('autonomous-custom-element', { is: 'is-custom-element'});
 
     assert_true(instance instanceof AutonomousCustomElement);
     assert_equals(instance.localName, 'autonomous-custom-element');
     assert_equals(instance.namespaceURI, 'http://www.w3.org/1999/xhtml', 'A custom element HTML must use HTML namespace');
 
+    var instance2 = document.createElement('undefined-element', { is: 'is-custom-element'});
+    assert_false(instance2.matches(':defined'));
+    class DefinedLater extends HTMLElement {}
+    customElements.define('undefined-element', DefinedLater);
+    document.body.appendChild(instance2);
+    assert_true(instance2 instanceof DefinedLater);
 }, 'document.createElement must create an instance of autonomous custom elements when it has is attribute');
 
 function assert_reports(expected, testFunction, message) {
@@ -349,6 +355,7 @@ test(() => {
   // https://github.com/w3c/webcomponents/issues/608
   let div = document.createElement('div', { is: 'my-div' });
   assert_false(div instanceof MyElement);
+  assert_false(div.hasAttribute('is'));
 
   customElements.define('my-div', MyElement, { extends: 'div' });
   document.body.appendChild(div);
diff --git a/tests/wpt/web-platform-tests/custom-elements/Document-createElementNS.html b/tests/wpt/web-platform-tests/custom-elements/Document-createElementNS.html
index ed30d0d4733..4cc4561f54c 100644
--- a/tests/wpt/web-platform-tests/custom-elements/Document-createElementNS.html
+++ b/tests/wpt/web-platform-tests/custom-elements/Document-createElementNS.html
@@ -38,6 +38,7 @@ test(() => {
   let element = document.createElementNS('http://www.w3.org/1999/xhtml', 'p:address', { is: 'my-builtin'});
   assert_true(element instanceof MyBuiltinElement);
   assert_equals(element.prefix, 'p');
+  assert_false(element.hasAttribute('is'));
 }, 'builtin: document.createElementNS should create custom elements with prefixes.');
 
 test(() => {
@@ -46,6 +47,7 @@ test(() => {
   customElements.define('my-builtin2', MyBuiltinElement2, { extends: 'address'});
   let element = document.createElementNS('urn:example', 'address', { is: 'my-builtin2' });
   assert_false(element instanceof MyBuiltinElement2);
+  assert_false(element.hasAttribute('is'));
 }, 'builtin: document.createElementNS should check namespaces.');
 </script>
 </body>
diff --git a/tests/wpt/web-platform-tests/custom-elements/builtin-coverage.html b/tests/wpt/web-platform-tests/custom-elements/builtin-coverage.html
index d9d3007f452..bd084e968a4 100644
--- a/tests/wpt/web-platform-tests/custom-elements/builtin-coverage.html
+++ b/tests/wpt/web-platform-tests/custom-elements/builtin-coverage.html
@@ -800,17 +800,24 @@ for (const t of testData) {
     test(() => {
       let customized = new t.klass();
       assert_equals(customized.constructor, t.klass);
+      assert_equals(customized.cloneNode().constructor, t.klass,
+                    'Cloning a customized built-in element should succeed.');
     }, `${t.tag}: Operator 'new' should instantiate a customized built-in element`);
 
     test(() => {
       let customized = document.createElement(t.tag, { is: name });
       assert_equals(customized.constructor, t.klass);
+      assert_equals(customized.cloneNode().constructor, t.klass,
+                    'Cloning a customized built-in element should succeed.');
     }, `${t.tag}: document.createElement() should instantiate a customized built-in element`);
 
     if (t.parsing == 'document') {
       let test = async_test(`${t.tag}: document parser should instantiate a customized built-in element`);
       window.addEventListener('load', test.step_func_done(() => {
-        assert_equals(document.querySelector(t.tag).constructor, t.klass);
+        let customized = document.querySelector(t.tag);
+        assert_equals(customized.constructor, t.klass);
+        assert_equals(customized.cloneNode().constructor, t.klass,
+                      'Cloning a customized built-in element should succeed.');
       }));
       return;
     }
@@ -823,6 +830,8 @@ for (const t of testData) {
       }
       let customized = document.getElementById(name);
       assert_equals(customized.constructor, t.klass);
+      assert_equals(customized.cloneNode().constructor, t.klass,
+                    'Cloning a customized built-in element should succeed.');
     }, `${t.tag}: innerHTML should instantiate a customized built-in element`);
 
   }, `${t.tag}: Define a customized built-in element`);
diff --git a/tests/wpt/web-platform-tests/custom-elements/upgrading/Document-importNode.html b/tests/wpt/web-platform-tests/custom-elements/upgrading/Document-importNode.html
new file mode 100644
index 00000000000..b80f90648d1
--- /dev/null
+++ b/tests/wpt/web-platform-tests/custom-elements/upgrading/Document-importNode.html
@@ -0,0 +1,56 @@
+<!DOCTYPE html>
+<link rel="help" href="https://dom.spec.whatwg.org/#dom-document-importnode">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../resources/custom-elements-helpers.js"></script>
+<body>
+<script>
+test_with_window((w, doc) => {
+  class MyElement extends HTMLElement {}
+  class MyElement2 extends w.HTMLElement {}
+  customElements.define('my-element', MyElement);
+  w.customElements.define('my-element', MyElement2);
+
+  let original = document.createElement('my-element');
+  assert_true(original instanceof MyElement);
+
+  let imported = doc.importNode(original);
+  assert_true(imported instanceof MyElement2);
+}, 'autonomous: document.importNode() should import custom elements successfully');
+
+test_with_window((w, doc) => {
+  class MyElement3 extends w.HTMLElement {}
+  w.customElements.define('my-element3', MyElement3);
+
+  let original = document.createElement('my-element3');
+  assert_equals(original.constructor, HTMLElement);
+
+  let imported = doc.importNode(original);
+  assert_true(imported instanceof MyElement3);
+}, 'autonomous: document.importNode() should import "undefined" custom elements successfully');
+
+test_with_window((w, doc) => {
+  class MyDiv extends HTMLDivElement {}
+  class MyDiv2 extends w.HTMLDivElement {}
+  customElements.define('my-div', MyDiv, { extends: 'div' });
+  w.customElements.define('my-div', MyDiv2, { extends: 'div' });
+
+  let original = document.createElement('div', { is: 'my-div' });
+  assert_true(original instanceof MyDiv);
+
+  let imported = doc.importNode(original);
+  assert_true(imported instanceof MyDiv2);
+}, 'built-in: document.importNode() should import custom elements successfully');
+
+test_with_window((w, doc) => {
+  class MyDiv2 extends w.HTMLDivElement {}
+  w.customElements.define('my-div2', MyDiv2, { extends: 'div' });
+
+  let original = document.createElement('div', { is: 'my-div2' });
+  assert_equals(original.constructor, HTMLDivElement);
+
+  let imported = doc.importNode(original);
+  assert_true(imported instanceof MyDiv2);
+}, 'built-in: document.importNode() should import "undefined" custom elements successfully');
+</script>
+</body>
diff --git a/tests/wpt/web-platform-tests/custom-elements/upgrading/Node-cloneNode.html b/tests/wpt/web-platform-tests/custom-elements/upgrading/Node-cloneNode.html
index 0492e1f39a1..1a8786e914b 100644
--- a/tests/wpt/web-platform-tests/custom-elements/upgrading/Node-cloneNode.html
+++ b/tests/wpt/web-platform-tests/custom-elements/upgrading/Node-cloneNode.html
@@ -49,6 +49,35 @@ test(function () {
         'A cloned custom element must be an instance of the custom element');
 }, 'Node.prototype.cloneNode(false) must be able to clone as a autonomous custom element when it contains is attribute');
 
+test(function () {
+    class MyDiv1 extends HTMLDivElement {};
+    class MyDiv2 extends HTMLDivElement {};
+    class MyDiv3 extends HTMLDivElement {};
+    customElements.define('my-div1', MyDiv1, { extends: 'div' });
+    customElements.define('my-div2', MyDiv2, { extends: 'div' });
+
+    let instance = document.createElement('div', { is: 'my-div1'});
+    assert_true(instance instanceof MyDiv1);
+    instance.setAttribute('is', 'my-div2');
+    let clone = instance.cloneNode(false);
+    assert_not_equals(instance, clone);
+    assert_true(clone instanceof MyDiv1,
+        'A cloned custom element must be an instance of the custom element even with an inconsistent "is" attribute');
+
+    let instance3 = document.createElement('div', { is: 'my-div3'});
+    assert_false(instance3 instanceof MyDiv3);
+    instance3.setAttribute('is', 'my-div2');
+    let clone3 = instance3.cloneNode(false);
+    assert_not_equals(instance3, clone);
+    customElements.define('my-div3', MyDiv3, { extends: 'div' });
+    document.body.appendChild(instance3);
+    document.body.appendChild(clone3);
+    assert_true(instance3 instanceof MyDiv3,
+        'An undefined element must be upgraded even with an inconsistent "is" attribute');
+    assert_true(clone3 instanceof MyDiv3,
+        'A cloned undefined element must be upgraded even with an inconsistent "is" attribute');
+}, 'Node.prototype.cloneNode(false) must be able to clone as a customized built-in element when it has an inconsistent "is" attribute');
+
 test_with_window(function (contentWindow) {
     var contentDocument = contentWindow.document;
     class MyCustomElement extends contentWindow.HTMLElement {}
diff --git a/tests/wpt/web-platform-tests/docs/introduction.md b/tests/wpt/web-platform-tests/docs/introduction.md
index c718efdb2ff..8833d869470 100644
--- a/tests/wpt/web-platform-tests/docs/introduction.md
+++ b/tests/wpt/web-platform-tests/docs/introduction.md
@@ -102,17 +102,22 @@ your `%Path%` [Environment Variable](http://www.computerhope.com/issues/ch000549
 and read the [Windows Notes](#windows-notes) section below.
 
 To get the tests running, you need to set up the test domains in your
-[`hosts` file](http://en.wikipedia.org/wiki/Hosts_%28file%29%23Location_in_the_file_system). The
-following entries are required:
+[`hosts` file](http://en.wikipedia.org/wiki/Hosts_%28file%29%23Location_in_the_file_system).
 
+The necessary content can be generated with `./wpt make-hosts-file`; on
+Windows, you will need to preceed the prior command with `python` or
+the path to the Python binary (`python wpt make-hosts-file`).
+
+For example, on most UNIX-like systems, you can setup the hosts file with:
+
+```bash
+./wpt make-hosts-file | sudo tee -a /etc/hosts
 ```
-127.0.0.1   web-platform.test
-127.0.0.1   www.web-platform.test
-127.0.0.1   www1.web-platform.test
-127.0.0.1   www2.web-platform.test
-127.0.0.1   xn--n8j6ds53lwwkrqhv28a.web-platform.test
-127.0.0.1   xn--lve-6lad.web-platform.test
-0.0.0.0     nonexistent-origin.web-platform.test
+
+And on Windows (note this requires an Administrator privileged shell):
+
+```bash
+python wpt make-hosts-file >> %SystemRoot%\System32\drivers\etc\hosts
 ```
 
 If you are behind a proxy, you also need to make sure the domains above are
diff --git a/tests/wpt/web-platform-tests/domparsing/XMLSerializer-serializeToString.html b/tests/wpt/web-platform-tests/domparsing/XMLSerializer-serializeToString.html
index 23323b98635..92cdb1068a6 100644
--- a/tests/wpt/web-platform-tests/domparsing/XMLSerializer-serializeToString.html
+++ b/tests/wpt/web-platform-tests/domparsing/XMLSerializer-serializeToString.html
@@ -39,6 +39,15 @@ test(function() {
   var xmlString = (new XMLSerializer()).serializeToString(root);
   assert_equals(xmlString, '<root xmlns="urn:bar"><outer xmlns=""><inner>value1</inner></outer></root>');
 }, 'Check if there is no redundant empty namespace declaration.');
+
+test(function() {
+  var serializer = new XMLSerializer();
+  var root = createXmlDoc().documentElement;
+  root.firstChild.setAttribute('attr1', 'value1\tvalue2\r\n');
+  var xmlString = serializer.serializeToString(root);
+  assert_equals(xmlString, '<root><child1 attr1="value1&#9;value2&#xD;&#xA;">value1</child1></root>');
+}, 'check XMLSerializer.serializeToString escapes attribute values for roundtripping');
+
 </script>
  </body>
 </html>
diff --git a/tests/wpt/web-platform-tests/fetch/corb/README.md b/tests/wpt/web-platform-tests/fetch/corb/README.md
new file mode 100644
index 00000000000..00e8c1648c1
--- /dev/null
+++ b/tests/wpt/web-platform-tests/fetch/corb/README.md
@@ -0,0 +1,21 @@
+# Tests related to Cross-Origin Resource Blocking (CORB).
+
+This directory contains tests related to the
+[Cross-Origin Resource Blocking (CORB)](https://chromium.googlesource.com/chromium/src/+/master/content/browser/loader/cross_origin_read_blocking_explainer.md) algorithm.
+
+Note that CORB is currently in very early stages of standardization path.  At
+the same time, some tests in this directory (e.g.
+`css-with-json-parser-breaker`) cover behavior spec-ed outside of CORB (making
+sure that CORB doesn't change the existing web behavior) and therefore are
+valuable independently from CORB's standardization efforts.
+
+Tests that cover behavior that is changed by CORB have to be marked as
+[tentative](http://web-platform-tests.org/writing-tests/file-names.html)
+(using `.tentative` substring in their filename) until CORB
+is included in the official
+[Fetch spec](https://fetch.spec.whatwg.org/).
+
+The tests in this directory interact with various, random features,
+but the tests have been grouped together into the `fetch/corb` directory,
+because all of these tests verify behavior that is important to the CORB
+algorithm.
diff --git a/tests/wpt/web-platform-tests/fetch/corb/css-with-json-parser-breaker.sub.html b/tests/wpt/web-platform-tests/fetch/corb/css-with-json-parser-breaker.sub.html
new file mode 100644
index 00000000000..9d930f9b8a8
--- /dev/null
+++ b/tests/wpt/web-platform-tests/fetch/corb/css-with-json-parser-breaker.sub.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CORB should not block text/css with a JSON parser breaker</title>
+<link rel="stylesheet" type="text/css"
+      href="http://{{domains[www1]}}:{{ports[http][0]}}/fetch/corb/resources/css-with-json-parser-breaker.css">
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<body>
+  <h1 id="header">Header example</h1>
+  <p>Paragraph body</p>
+</body>
+<script>
+test(function() {
+  var style = getComputedStyle(document.getElementById('header'));
+  assert_equals(style.getPropertyValue('color'), 'rgb(255, 0, 0)');
+}, "CORB should not block text/css with a JSON parser breaker");
+</script>
diff --git a/tests/wpt/web-platform-tests/fetch/corb/resources/css-with-json-parser-breaker.css b/tests/wpt/web-platform-tests/fetch/corb/resources/css-with-json-parser-breaker.css
new file mode 100644
index 00000000000..3ba33659844
--- /dev/null
+++ b/tests/wpt/web-platform-tests/fetch/corb/resources/css-with-json-parser-breaker.css
@@ -0,0 +1,3 @@
+)]}'
+{}
+h1 { color: red; }
diff --git a/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/cross-origin-objects.html b/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/cross-origin-objects.html
index 2820b75b21d..e0b4b0c9da9 100644
--- a/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/cross-origin-objects.html
+++ b/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/cross-origin-objects.html
@@ -11,6 +11,7 @@
 <div id=log></div>
 <iframe id="B"></iframe>
 <iframe id="C"></iframe>
+<iframe id="D"></iframe>
 <script>
 
 /*
@@ -21,10 +22,13 @@ var host_info = get_host_info();
 
 setup({explicit_done: true});
 path = location.pathname.substring(0, location.pathname.lastIndexOf('/')) + '/frame.html';
+pathWithThen = location.pathname.substring(0, location.pathname.lastIndexOf('/')) + '/frame-with-then.html';
 var B = document.getElementById('B').contentWindow;
 var C = document.getElementById('C').contentWindow;
+var D = document.getElementById('D').contentWindow;
 B.frameElement.uriToLoad = path;
 C.frameElement.uriToLoad = get_host_info().HTTP_REMOTE_ORIGIN + path;
+D.frameElement.uriToLoad = get_host_info().HTTP_REMOTE_ORIGIN + pathWithThen;
 
 function reloadSubframes(cb) {
   var iframes = document.getElementsByTagName('iframe');
@@ -45,8 +49,8 @@ function isObject(x) { return Object(x) === x; }
  */
 
 var testList = [];
-function addTest(fun, desc) { testList.push([fun, desc]); }
-
+function addTest(func, desc) { testList.push({func, desc, promiseTest: false}); }
+function addPromiseTest(func, desc) { testList.push({func, desc, promiseTest: true}); }
 
 /*
  * Basic sanity testing.
@@ -72,10 +76,10 @@ addTest(function() {
 
 var whitelistedWindowIndices = ['0', '1'];
 var whitelistedWindowPropNames = ['location', 'postMessage', 'window', 'frames', 'self', 'top', 'parent',
-                                  'opener', 'closed', 'close', 'blur', 'focus', 'length'];
+                                  'opener', 'closed', 'close', 'blur', 'focus', 'length', 'then'];
 whitelistedWindowPropNames = whitelistedWindowPropNames.concat(whitelistedWindowIndices);
 whitelistedWindowPropNames.sort();
-var whitelistedLocationPropNames = ['href', 'replace'];
+var whitelistedLocationPropNames = ['href', 'replace', 'then'];
 whitelistedLocationPropNames.sort();
 var whitelistedSymbols = [Symbol.toStringTag, Symbol.hasInstance,
                           Symbol.isConcatSpreadable];
@@ -191,7 +195,7 @@ function checkPropertyDescriptor(desc, propName, expectWritable) {
   assert_equals(desc.configurable, true, "property descriptor for " + propName + " should be configurable");
   if (!isArrayIndexPropertyName) {
     assert_equals(desc.enumerable, false, "property descriptor for " + propName + " should not be enumerable");
-    if(isSymbol) {
+    if (isSymbol || propName == "then") {
       assert_true("value" in desc,
                   "property descriptor for " + propName + " should be a value descriptor");
       assert_equals(desc.value, undefined,
@@ -222,6 +226,10 @@ addTest(function() {
   });
 }, "[[GetOwnProperty]] - Property descriptors for cross-origin properties should be set up correctly");
 
+addTest(function() {
+  assert_equals(typeof D.then, "object");
+}, "[[GetOwnProperty]] - Subframe named 'then' should shadow the default 'then' value");
+
 /*
  * [[Delete]]
  */
@@ -309,6 +317,10 @@ addTest(function() {
   indexedWindowProps = allWindowProps.slice(0, whitelistedWindowIndices.length);
   stringWindowProps = allWindowProps.slice(0, -1 * whitelistedSymbols.length);
   symbolWindowProps = allWindowProps.slice(-1 * whitelistedSymbols.length);
+  // stringWindowProps should have "then" last in this case.  Do this
+  // check before we call stringWindowProps.sort() below.
+  assert_equals(stringWindowProps[stringWindowProps.length - 1], "then",
+                "'then' property should be added to the end of the string list if not there");
   assert_array_equals(indexedWindowProps, whitelistedWindowIndices,
                       "Reflect.ownKeys should start with the indices exposed on the cross-origin window.");
   assert_array_equals(stringWindowProps.sort(), whitelistedWindowPropNames,
@@ -325,6 +337,17 @@ addTest(function() {
                       "Reflect.ownKeys should end with the cross-origin symbols for a cross-origin Location.")
 }, "[[OwnPropertyKeys]] should place the symbols after the property names after the subframe indices");
 
+addTest(function() {
+  var stringProps = Object.getOwnPropertyNames(D);
+  // Named frames are not exposed via [[OwnPropertyKeys]].
+  assert_equals(stringProps.indexOf("a"), -1);
+  assert_equals(stringProps.indexOf("b"), -1);
+  assert_equals(typeof D.a, "object");
+  assert_equals(typeof D.b, "object");
+  assert_equals(stringProps[stringProps.length - 1], "then");
+  assert_equals(stringProps.indexOf("then"), stringProps.lastIndexOf("then"));
+}, "[[OwnPropertyKeys]] should not reorder where 'then' appears if it's a named subframe, nor add another copy of 'then'");
+
 addTest(function() {
   assert_true(B.eval('parent.C') === C, "A and B observe the same identity for C's Window");
   assert_true(B.eval('parent.C.location') === C.location, "A and B observe the same identity for C's Location");
@@ -393,16 +416,43 @@ addTest(function() {
   assert_equals({}.toString.call(C.location), "[object Object]");
 }, "{}.toString.call() does the right thing on cross-origin objects");
 
+addPromiseTest(function() {
+  return Promise.resolve(C).then((arg) => {
+    assert_equals(arg, C);
+  });
+}, "Resolving a promise with a cross-origin window without a 'then' subframe should work.");
+
+addPromiseTest(function() {
+  return Promise.resolve(D).then((arg) => {
+    assert_equals(arg, D);
+  });
+}, "Resolving a promise with a cross-origin window with a 'then' subframe should work.");
+
+addPromiseTest(function() {
+  return Promise.resolve(D.location).then((arg) => {
+    assert_equals(arg, D.location);
+  });
+}, "Resolving a promise with a cross-origin location should work.");
+
 // We do a fresh load of the subframes for each test to minimize side-effects.
 // It would be nice to reload ourselves as well, but we can't do that without
 // disrupting the test harness.
+function testDone() {
+  if (testList.length != 0) {
+    reloadSubframes(runNextTest);
+  } else {
+    done();
+  }
+}
+
 function runNextTest() {
   var entry = testList.shift();
-  test(() => entry[0](), entry[1])
-  if (testList.length != 0)
-    reloadSubframes(runNextTest);
-  else
-    done();
+  if (entry.promiseTest) {
+    promise_test(() => entry.func().finally(testDone), entry.desc);
+  } else {
+    test(entry.func, entry.desc);
+    testDone();
+  }
 }
 reloadSubframes(runNextTest);
 
diff --git a/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/frame-with-then.html b/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/frame-with-then.html
new file mode 100644
index 00000000000..96cdf1ea99b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/frame-with-then.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<html>
+  <body>
+    <!--- Some frames to test ordering -->
+    <iframe name="a"></iframe>
+    <!-- A subframe to test "then" behavior -->
+    <iframe name="then"></iframe>
+    <iframe name="b"></iframe>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/frame.html b/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/frame.html
index 341da6a9788..0d81624597d 100644
--- a/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/frame.html
+++ b/tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/frame.html
@@ -6,6 +6,10 @@
   // properly ignored cross-origin.
   window.frames = "override";
 
+  // Also add a |then| property to test that it doesn't get exposed.
+  window.then = "something";
+  window.location.then = "something-else";
+
   // If we get a postMessage, we grab references to everything and set
   // document.domain to trim off our topmost subdomain.
   window.onmessage = function(evt) {
diff --git a/tests/wpt/web-platform-tests/html/dom/documents/dom-tree-accessors/Document.body.html b/tests/wpt/web-platform-tests/html/dom/documents/dom-tree-accessors/Document.body.html
index 7d8548885a6..f4212502956 100644
--- a/tests/wpt/web-platform-tests/html/dom/documents/dom-tree-accessors/Document.body.html
+++ b/tests/wpt/web-platform-tests/html/dom/documents/dom-tree-accessors/Document.body.html
@@ -216,4 +216,12 @@ test(function() {
   assert_equals(f2.nextSibling, f1, "New frameset should have replaced the body");
 }, "Setting document.body to a frameset will replace the first existing body/frameset.");
 
+test(function() {
+  var doc = createDocument();
+  doc.appendChild(doc.createElement("test"));
+  var new_body = doc.createElement("body");
+  doc.body = new_body;
+  assert_equals(doc.documentElement.firstChild, new_body, "new_body should be inserted");
+  assert_equals(doc.body, null, "Getter should return null when the root is not html");
+}, "Setting document.body to a new body element when the root element is a test element.");
 </script>
diff --git a/tests/wpt/web-platform-tests/html/infrastructure/common-dom-interfaces/collections/historical.html b/tests/wpt/web-platform-tests/html/infrastructure/common-dom-interfaces/collections/historical.html
index a26dd4ccd45..ef8345aa724 100644
--- a/tests/wpt/web-platform-tests/html/infrastructure/common-dom-interfaces/collections/historical.html
+++ b/tests/wpt/web-platform-tests/html/infrastructure/common-dom-interfaces/collections/historical.html
@@ -5,6 +5,8 @@
 <div id=log></div>
 <form id=form><input name=foo></form>
 <select id=select><option name=bar></select>
+<div id=dupe>
+<div id=dupe>
 <script>
 test(function() {
   var collection = document.getElementById('form').elements;
@@ -22,4 +24,10 @@ test(function() {
   });
 }, 'HTMLOptionsCollection legacycaller should not be supported');
 
+test(function() {
+  var collection = document.all('dupe', 0);
+  // If the second argument were used, it would return the first item of the
+  // collection instead of the whole collection.
+  assert_equals(collection.length, 2, 'length');
+}, 'HTMLAllCollection legacycaller with two arguments should not be supported');
 </script>
diff --git a/tests/wpt/web-platform-tests/html/infrastructure/common-dom-interfaces/collections/htmlallcollection.html b/tests/wpt/web-platform-tests/html/infrastructure/common-dom-interfaces/collections/htmlallcollection.html
index e17c0eb82fd..d42599661bf 100644
--- a/tests/wpt/web-platform-tests/html/infrastructure/common-dom-interfaces/collections/htmlallcollection.html
+++ b/tests/wpt/web-platform-tests/html/infrastructure/common-dom-interfaces/collections/htmlallcollection.html
@@ -22,6 +22,7 @@
 <div id="undefined"></div>
 <div id="null"></div>
 <div name="divwithname"></div>
+<div id="-0"></div>
 <script>
 var anchors = document.querySelectorAll("a");
 var divs = document.querySelectorAll("div");
@@ -33,19 +34,20 @@ test(function() {
 }, "document.all is an HTMLAllCollection");
 
 test(function() {
-  assert_equals(document.all.length, 23);
+  assert_equals(document.all.length, 24);
 }, "length attribute");
 
 // indexed property getter
 
 test(function() {
   assert_equals(document.all[0], document.documentElement);
-  assert_equals(document.all[22], scripts[2]);
+  assert_equals(document.all[-0], document.documentElement);
+  assert_equals(document.all[23], scripts[2]);
 }, "indexed property getter");
 
 test(function() {
   assert_equals(document.all[-1], undefined);
-  assert_equals(document.all[23], undefined);
+  assert_equals(document.all[24], undefined);
   assert_equals(document.all[42], undefined);
   assert_equals(document.all[43], undefined);
   assert_equals(document.all[4294967294], undefined);
@@ -84,8 +86,8 @@ test(function() {
 
 test(function() {
   assert_equals(document.all["0"], document.documentElement);
-  assert_equals(document.all["22"], document.scripts[2]);
-  assert_equals(document.all["23"], undefined);
+  assert_equals(document.all["23"], document.scripts[2]);
+  assert_equals(document.all["24"], undefined);
   assert_equals(document.all["42"], undefined);
   assert_equals(document.all["43"], undefined);
 }, "named property getter with \"array index property name\"");
@@ -97,6 +99,7 @@ test(function() {
   assert_equals(document.all["4294967294"], undefined);
   assert_equals(document.all["4294967295"], divs[1]);
   assert_equals(document.all["4294967296"], divs[2]);
+  assert_equals(document.all["-0"], divs[6]);
 }, "named property getter with invalid \"array index property name\"");
 
 test(function() {
@@ -130,8 +133,8 @@ test(function() {
 
 test(function() {
   assert_equals(document.all.namedItem("0"), null);
-  assert_equals(document.all.namedItem("22"), null);
   assert_equals(document.all.namedItem("23"), null);
+  assert_equals(document.all.namedItem("24"), null);
   assert_equals(document.all.namedItem("42"), spans[0]);
   assert_equals(document.all.namedItem("43"), null);
 }, "namedItem method with \"array index property name\"");
@@ -143,6 +146,7 @@ test(function() {
   assert_equals(document.all.namedItem("4294967294"), divs[0]);
   assert_equals(document.all.namedItem("4294967295"), divs[1]);
   assert_equals(document.all.namedItem("4294967296"), divs[2]);
+  assert_equals(document.all.namedItem("-0"), divs[6]);
 }, "namedItem method with invalid \"array index property name\"");
 
 test(function() {
@@ -183,16 +187,16 @@ test(function() {
 
 test(function() {
   assert_equals(document.all("0"), document.documentElement);
-  assert_equals(document.all("22"), document.scripts[2]);
-  assert_equals(document.all("23"), null);
+  assert_equals(document.all("23"), document.scripts[2]);
+  assert_equals(document.all("24"), null);
   assert_equals(document.all("42"), null);
   assert_equals(document.all("43"), null);
 }, "legacy caller with \"array index property name\"");
 
 test(function() {
   assert_equals(document.all(0), document.documentElement);
-  assert_equals(document.all(22), document.scripts[2]);
-  assert_equals(document.all(23), null);
+  assert_equals(document.all(23), document.scripts[2]);
+  assert_equals(document.all(24), null);
   assert_equals(document.all(42), null);
   assert_equals(document.all(43), null);
 }, "legacy caller with \"array index property name\" as number");
@@ -204,6 +208,7 @@ test(function() {
   assert_equals(document.all("4294967294"), null);
   assert_equals(document.all("4294967295"), divs[1]);
   assert_equals(document.all("4294967296"), divs[2]);
+  assert_equals(document.all("-0"), divs[6]);
 }, "legacy caller with invalid \"array index property name\"");
 
 test(function() {
@@ -262,16 +267,16 @@ test(function() {
 
 test(function() {
   assert_equals(document.all.item("0"), document.documentElement);
-  assert_equals(document.all.item("22"), document.scripts[2]);
-  assert_equals(document.all.item("23"), null);
+  assert_equals(document.all.item("23"), document.scripts[2]);
+  assert_equals(document.all.item("24"), null);
   assert_equals(document.all.item("42"), null);
   assert_equals(document.all.item("43"), null);
 }, "item method with \"array index property name\"");
 
 test(function() {
   assert_equals(document.all.item(0), document.documentElement);
-  assert_equals(document.all.item(22), document.scripts[2]);
-  assert_equals(document.all.item(23), null);
+  assert_equals(document.all.item(23), document.scripts[2]);
+  assert_equals(document.all.item(24), null);
   assert_equals(document.all.item(42), null);
   assert_equals(document.all.item(43), null);
 }, "item method with \"array index property name\" as number");
@@ -283,6 +288,7 @@ test(function() {
   assert_equals(document.all.item("4294967294"), null);
   assert_equals(document.all.item("4294967295"), divs[1]);
   assert_equals(document.all.item("4294967296"), divs[2]);
+  assert_equals(document.all.item("-0"), divs[6]);
 }, "item method with invalid \"array index property name\"");
 
 test(function() {
diff --git a/tests/wpt/web-platform-tests/html/obsolete/requirements-for-implementations/other-elements-attributes-and-apis/document-color-01.html b/tests/wpt/web-platform-tests/html/obsolete/requirements-for-implementations/other-elements-attributes-and-apis/document-color-01.html
index 38364cd3e65..e6f0c2b573e 100644
--- a/tests/wpt/web-platform-tests/html/obsolete/requirements-for-implementations/other-elements-attributes-and-apis/document-color-01.html
+++ b/tests/wpt/web-platform-tests/html/obsolete/requirements-for-implementations/other-elements-attributes-and-apis/document-color-01.html
@@ -7,47 +7,89 @@
 <script src="/resources/testharnessreport.js"></script>
 <div id="log"></div>
 <script>
+function setColorAttributes(doc, color) {
+  doc.fgColor = color;
+  doc.bgColor = color;
+  doc.linkColor = color;
+  doc.vlinkColor = color;
+  doc.alinkColor = color;
+}
+
+function checkColorAttributes(doc, expected) {
+  assert_equals(document.fgColor, expected);
+  assert_equals(document.bgColor, expected);
+  assert_equals(document.linkColor, expected);
+  assert_equals(document.vlinkColor, expected);
+  assert_equals(document.alinkColor, expected);
+}
+
 test(function() {
-  document.fgColor = "green";
-  document.bgColor = "green";
-  document.linkColor = "green";
-  document.vlinkColor = "green";
-  document.alinkColor = "green";
+  setColorAttributes(document, 'green');
 
   var body = document.documentElement.removeChild(document.body);
-
+  this.add_cleanup(function() {
+    // Re-add body and reset color attributes.
+    document.body = body;
+    setColorAttributes(document, '');
+  });
   // When there is no body element, the color attributes return an
   // empty string upon getting.
-  assert_equals(document.fgColor, "");
-  assert_equals(document.bgColor, "");
-  assert_equals(document.linkColor, "");
-  assert_equals(document.vlinkColor, "");
-  assert_equals(document.alinkColor, "");
-
-  // Re-add body and reset color attributes.
-  document.body = body;
-  document.fgColor = "";
-  document.bgColor = "";
-  document.linkColor = "";
-  document.vlinkColor = "";
-  document.alinkColor = "";
+  checkColorAttributes(document, '');
 }, "getting document color attributes with no body");
 
 test(function() {
   var body = document.documentElement.removeChild(document.body);
+  this.add_cleanup(function() {
+    document.body = body;
+  });
 
   // When there is no body element, setting the color attributes has no effect.
-  document.fgColor = "red";
-  document.bgColor = "red";
-  document.linkColor = "red";
-  document.vlinkColor = "red";
-  document.alinkColor = "red";
-  assert_equals(document.fgColor, "");
-  assert_equals(document.bgColor, "");
-  assert_equals(document.linkColor, "");
-  assert_equals(document.vlinkColor, "");
-  assert_equals(document.alinkColor, "");
-
-  document.body = body;
+  setColorAttributes(document, 'red');
+  checkColorAttributes(document, '');
 }, "setting document color attributes with no body");
+
+function testBogusRootElement(doc) {
+  doc.replaceChild(doc.createElement('test'), doc.documentElement);
+  var new_body = doc.createElement('body');
+  doc.documentElement.appendChild(new_body);
+
+  setColorAttributes(doc, 'red');
+
+  assert_equals(new_body.attributes.length, 0, 'new_body.attributes.length');
+  checkColorAttributes(doc, '');
+}
+
+function createIframeDoc(markup) {
+  var iframe = document.createElement('iframe');
+  document.body.appendChild(iframe);
+  var doc = iframe.contentDocument;
+  doc.open();
+  doc.write(markup);
+  doc.close();
+  return doc;
+}
+
+test(function() {
+  // Use standards mode for doc
+  var doc = createIframeDoc('<!doctype html>');
+  testBogusRootElement(doc);
+}, "document color attributes when the root element is a test element (iframe)");
+
+test(function() {
+  var doc = document.implementation.createHTMLDocument();
+  testBogusRootElement(doc);
+}, "document color attributes when the root element is a test element (createHTMLDocument)");
+
+test(function() {
+  var doc = createIframeDoc('<!doctype html><frameset text=red link=red vlink=red alink=red bgcolor=red>');
+  assert_equals(doc.body.attributes.length, 5, 'attributes.length on the frameset');
+  checkColorAttributes(doc, '');
+}, "getting document color attributes when document.body is a frameset");
+
+test(function() {
+  var doc = createIframeDoc('<!doctype html><frameset>');
+  setColorAttributes(doc, 'red');
+  assert_equals(doc.body.attributes.length, 0, 'attributes.length on the frameset');
+  checkColorAttributes(doc, '');
+}, "setting document color attributes when document.body is a frameset");
 </script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/emptyish-script-elements.html b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/emptyish-script-elements.html
new file mode 100644
index 00000000000..37f4a87c95e
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/scripting-1/the-script-element/emptyish-script-elements.html
@@ -0,0 +1,75 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Treatment of various empty-ish script elements</title>
+<link rel="author" title="Domenic Denicola" href="mailto:d@domenic.me">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#prepare-a-script">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#already-started">
+<link rel="help" href="https://github.com/whatwg/html/issues/3419">
+
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<script id="no-children"></script>
+<script id="whitespace-child"> </script>
+
+<script id="gets-a-no-text-child"></script>
+<script id="gets-an-empty-text-child"></script>
+<script id="gets-a-text-child"></script>
+<script id="gets-a-comment-child"></script>
+<script id="gets-a-text-descendant"></script>
+
+<script>
+"use strict";
+
+test(() => {
+  const el = document.querySelector("#no-children");
+  el.appendChild(document.createTextNode("window.noChildrenExecuted = true;"));
+  assert_true(window.noChildrenExecuted);
+}, "A script with no children bails early, before setting already-started, so can be executed when adding text");
+
+test(() => {
+  const el = document.querySelector("#whitespace-child");
+  el.appendChild(document.createTextNode("window.whitespaceChildExecuted = true;"));
+  assert_equals(window.whitespaceChildExecuted, undefined);
+}, "A script with a whitespace child executes, setting already-started, so adding text is a no-op");
+
+test(() => {
+  const el = document.querySelector("#gets-a-no-text-child");
+  el.appendChild(document.createElement("span"));
+  el.appendChild(document.createTextNode("window.getsANoTextChildExecuted = true;"));
+  assert_true(window.getsANoTextChildExecuted);
+}, "A script with an empty element inserted bails early, before setting already-started, so can be executed when adding text");
+
+test(() => {
+  const el = document.querySelector("#gets-an-empty-text-child");
+  el.appendChild(document.createTextNode(""));
+  el.appendChild(document.createTextNode("window.getsAnEmptyTextChildExecuted = true;"));
+  assert_true(window.getsAnEmptyTextChildExecuted);
+}, "A script with an empty text node inserted bails early, before setting already-started, so can be executed when adding text");
+
+test(() => {
+  const el = document.querySelector("#gets-a-text-child");
+  el.appendChild(document.createTextNode("window.getsATextChildExecuted1 = true;"));
+  el.appendChild(document.createTextNode("window.getsATextChildExecuted2 = true;"));
+  assert_true(window.getsATextChildExecuted1);
+  assert_equals(window.getsATextChildExecuted2, undefined);
+}, "A script with a text child inserted executes, setting already-started, so adding text is a no-op");
+
+test(() => {
+  const el = document.querySelector("#gets-a-comment-child");
+  el.appendChild(document.createComment("window.getsACommentChild1 = true;"));
+  el.appendChild(document.createTextNode("window.getsACommentChild2 = true;"));
+  assert_equals(window.getsACommentChild1, undefined);
+  assert_true(window.getsACommentChild2);
+}, "A script with a comment child inserted bails early, before setting already-started, so can be executed when adding text");
+
+test(() => {
+  const el = document.querySelector("#gets-a-text-descendant");
+  const child = document.createElement("span");
+  child.appendChild(document.createTextNode("window.getsATextDescendantExecuted1 = true;"));
+  el.appendChild(child);
+  el.appendChild(document.createTextNode("window.getsATextDescendantExecuted2 = true;"));
+  assert_equals(window.getsATextDescendantExecuted1, undefined);
+  assert_true(window.getsATextDescendantExecuted2);
+}, "A script with an element containing text inserted bails early, before setting already-started, so can be executed when adding text");
+</script>
diff --git a/tests/wpt/web-platform-tests/innerText/getter.html b/tests/wpt/web-platform-tests/innerText/getter.html
index 7a517db3d14..e6ba0db64b7 100644
--- a/tests/wpt/web-platform-tests/innerText/getter.html
+++ b/tests/wpt/web-platform-tests/innerText/getter.html
@@ -15,8 +15,6 @@
 <div id="container"></div>
 <svg id="svgContainer"></svg>
 <script>
-let container = document.querySelector('#container');
-let svgContainer = document.querySelector('#svgContainer');
 function testText(html, expectedPlain, msg) {
   textTextInContainer(container, html, expectedPlain, msg);
 }
diff --git a/tests/wpt/web-platform-tests/lint.whitelist b/tests/wpt/web-platform-tests/lint.whitelist
index 95f82eae4c7..d3dc4287de0 100644
--- a/tests/wpt/web-platform-tests/lint.whitelist
+++ b/tests/wpt/web-platform-tests/lint.whitelist
@@ -794,6 +794,8 @@ CSS-COLLIDING-REF-NAME: css/CSS2/visufx/overflow-applies-to-001-ref.xht
 CSS-COLLIDING-REF-NAME: css/CSS2/ui/overflow-applies-to-001-ref.xht
 CSS-COLLIDING-REF-NAME: css/CSS2/visuren/inline-formatting-context-001-ref.xht
 CSS-COLLIDING-REF-NAME: css/CSS2/linebox/inline-formatting-context-001-ref.xht
+CSS-COLLIDING-REF-NAME: css/css-transforms/individual-transform/individual-transform-1-ref.html
+CSS-COLLIDING-REF-NAME: css/vendor-imports/mozilla/mozilla-central-reftests/transforms/individual-transform-1-ref.html
 CSS-COLLIDING-SUPPORT-NAME: css/css-backgrounds/support/red.png
 CSS-COLLIDING-SUPPORT-NAME: css/compositing/mix-blend-mode/support/red.png
 CSS-COLLIDING-SUPPORT-NAME: css/compositing/background-blending/support/red.png
diff --git a/tests/wpt/web-platform-tests/media/foo-no-cors.vtt b/tests/wpt/web-platform-tests/media/foo-no-cors.vtt
new file mode 100644
index 00000000000..b533895c604
--- /dev/null
+++ b/tests/wpt/web-platform-tests/media/foo-no-cors.vtt
@@ -0,0 +1,4 @@
+WEBVTT
+
+00:00:00.000 --> 00:00:05.000
+Foo
diff --git a/tests/wpt/web-platform-tests/picture-in-picture/not-processing-user-gesture.html b/tests/wpt/web-platform-tests/picture-in-picture/not-processing-user-gesture.html
deleted file mode 100644
index 00758946b80..00000000000
--- a/tests/wpt/web-platform-tests/picture-in-picture/not-processing-user-gesture.html
+++ /dev/null
@@ -1,11 +0,0 @@
-<!DOCTYPE html>
-<title>Test request Picture-in-Picture requires a user gesture</title>
-<script src="/resources/testharness.js"></script>
-<script src="/resources/testharnessreport.js"></script>
-<body></body>
-<script>
-promise_test(t => {
-  return promise_rejects(t, 'NotAllowedError',
-      document.createElement('video').requestPictureInPicture());
-}, );
-</script>
diff --git a/tests/wpt/web-platform-tests/picture-in-picture/picture-in-picture-window.html b/tests/wpt/web-platform-tests/picture-in-picture/picture-in-picture-window.html
new file mode 100644
index 00000000000..4bee95d9039
--- /dev/null
+++ b/tests/wpt/web-platform-tests/picture-in-picture/picture-in-picture-window.html
@@ -0,0 +1,61 @@
+<!DOCTYPE html>
+<title>Test Picture-in-Picture window</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="resources/picture-in-picture-helpers.js"></script>
+<body></body>
+<script>
+promise_test(t => {
+  return requestPictureInPictureWithTrustedClick(document.createElement('video'))
+  .then(pipWindow => {
+    assert_not_equals(pipWindow.width, 0);
+    assert_not_equals(pipWindow.height, 0);
+  });
+}, 'Picture-in-Picture window dimensions are set after entering Picture-in-Picture');
+
+promise_test(t => {
+  const video1 = document.createElement('video');
+  const video2 = document.createElement('video');
+  return requestPictureInPictureWithTrustedClick(video1)
+  .then(pipWindow1 => {
+    return requestPictureInPictureWithTrustedClick(video2)
+    .then(pipWindow2 => {
+      assert_equals(pipWindow1.width, 0);
+      assert_equals(pipWindow1.height, 0);
+      assert_not_equals(pipWindow2.width, 0);
+      assert_not_equals(pipWindow2.height, 0);
+    });
+  });
+}, 'Picture-in-Picture window dimensions are set to 0 after entering ' +
+   'Picture-in-Picture for another video');
+
+promise_test(t => {
+  return requestPictureInPictureWithTrustedClick(document.createElement('video'))
+  .then(pipWindow => {
+    return document.exitPictureInPicture()
+    .then(() => {
+      assert_equals(pipWindow.width, 0);
+      assert_equals(pipWindow.height, 0);
+    });
+  })
+}, 'Picture-in-Picture window dimensions are set to 0 after exiting Picture-in-Picture');
+
+promise_test(t => {
+  const video = document.createElement('video');
+  let thePipWindow;
+
+  video.addEventListener('leavepictureinpicture', t.step_func_done(event => {
+    assert_equals(thePipWindow.width, 0);
+    assert_equals(thePipWindow.height, 0);
+  }));
+
+  return requestPictureInPictureWithTrustedClick(video)
+  .then(pipWindow => {
+    thePipWindow = pipWindow;
+    video.disablePictureInPicture = true;
+  });
+}, 'Picture-in-Picture window dimensions are set to 0 if ' +
+   'disablePictureInPicture becomes true');
+</script>
diff --git a/tests/wpt/web-platform-tests/picture-in-picture/request-picture-in-picture.html b/tests/wpt/web-platform-tests/picture-in-picture/request-picture-in-picture.html
index eaabcb7a205..32bbfc204b7 100644
--- a/tests/wpt/web-platform-tests/picture-in-picture/request-picture-in-picture.html
+++ b/tests/wpt/web-platform-tests/picture-in-picture/request-picture-in-picture.html
@@ -9,5 +9,21 @@
 <script>
 promise_test(t => {
   return requestPictureInPictureWithTrustedClick(document.createElement('video'));
-});
+}, 'request Picture-in-Picture resolves on user click');
+
+promise_test(t => {
+  return promise_rejects(t, 'NotAllowedError',
+      document.createElement('video').requestPictureInPicture());
+}, 'request Picture-in-Picture requires a user gesture');
+
+promise_test(t => {
+  return callWithTrustedClick(() => {
+    const first = document.createElement('video').requestPictureInPicture();
+    const second = document.createElement('video').requestPictureInPicture();
+    return Promise.all([
+      first,
+      promise_rejects(t, 'NotAllowedError', second)
+    ]);
+  });
+}, 'request Picture-in-Picture consumes user gesture');
 </script>
diff --git a/tests/wpt/web-platform-tests/picture-in-picture/shadow-dom.html b/tests/wpt/web-platform-tests/picture-in-picture/shadow-dom.html
new file mode 100644
index 00000000000..4f4c955d01e
--- /dev/null
+++ b/tests/wpt/web-platform-tests/picture-in-picture/shadow-dom.html
@@ -0,0 +1,57 @@
+<!DOCTYPE html>
+<title>Test for pictureInPictureElement adjustment for Shadow DOM</title>
+<script src='/resources/testharness.js'></script>
+<script src='/resources/testharnessreport.js'></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="resources/picture-in-picture-helpers.js"></script>
+<script src='../shadow-dom/resources/shadow-dom.js'></script>
+<body>
+<div id='host'>
+  <template data-mode='open' id='root'>
+    <slot></slot>
+  </template>
+  <div id='host2'>
+    <template data-mode='open' id='root2'>
+      <div id='host3'>
+        <template data-mode='open' id='root3'>
+          <video id='video'></video>
+          <div id='host4'>
+            <template data-mode='open' id='root4'>
+              <div></div>
+            </template>
+          </div>
+        </template>
+      </div>
+      <div id='host5'>
+        <template data-mode='open' id='root5'>
+          <div></div>
+        </template>
+      </div>
+    </template>
+  </div>
+</div>
+</body>
+<script>
+promise_test(t => {
+  const ids = createTestTree(host);
+  document.body.appendChild(ids.host);
+
+  assert_equals(document.pictureInPictureElement, null);
+  assert_equals(ids.root.pictureInPictureElement, null);
+  assert_equals(ids.root2.pictureInPictureElement, null);
+  assert_equals(ids.root3.pictureInPictureElement, null);
+  assert_equals(ids.root4.pictureInPictureElement, null);
+  assert_equals(ids.root5.pictureInPictureElement, null);
+
+  return requestPictureInPictureWithTrustedClick(ids.video)
+  .then(() => {
+    assert_equals(document.pictureInPictureElement, ids.host2);
+    assert_equals(ids.root.pictureInPictureElement, null);
+    assert_equals(ids.root2.pictureInPictureElement, ids.host3);
+    assert_equals(ids.root3.pictureInPictureElement, ids.video);
+    assert_equals(ids.root4.pictureInPictureElement, null);
+    assert_equals(ids.root5.pictureInPictureElement, null);
+  })
+});
+</script>
\ No newline at end of file
diff --git a/tests/wpt/web-platform-tests/resource-timing/clear_resource_timing_functionality.html b/tests/wpt/web-platform-tests/resource-timing/clear_resource_timing_functionality.html
new file mode 100644
index 00000000000..eaf21b483cc
--- /dev/null
+++ b/tests/wpt/web-platform-tests/resource-timing/clear_resource_timing_functionality.html
@@ -0,0 +1,26 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8" />
+<title>This test validates the functionality of clearResourceTimings method in resource timing.</title>
+<link rel="author" title="Intel" href="http://www.intel.com/" />
+<link rel="help" href="http://www.w3.org/TR/resource-timing/#performanceresourcetiming"/>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/webperftestharness.js"></script>
+<script src="resources/webperftestharnessextension.js"></script>
+<script>
+    setup({ explicit_done: true });
+    const context = new PerformanceContext(performance);
+    function onload_test()
+    {
+        test_equals(context.getEntriesByType('resource').length, 4, 4 + ' resource timing entries should be stored in this page.');
+        context.clearResourceTimings();
+        test_equals(context.getEntriesByType('resource').length, 0, 'No resource timing entries should be stored after clearResourceTimings.');
+        done();
+    }
+</script>
+</head>
+<body onload=onload_test()>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/resource-timing/resource_timing_TAO_cross_origin_redirect.html b/tests/wpt/web-platform-tests/resource-timing/resource_timing_TAO_cross_origin_redirect.html
new file mode 100644
index 00000000000..a91eaf8a1f6
--- /dev/null
+++ b/tests/wpt/web-platform-tests/resource-timing/resource_timing_TAO_cross_origin_redirect.html
@@ -0,0 +1,38 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8" />
+<title>This test validates the values in resource timing for a timing allowed cross-origin redirect.</title>
+<link rel="author" title="Intel" href="http://www.intel.com/" />
+<link rel="help" href="http://www.w3.org/TR/resource-timing/#performanceresourcetiming"/>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/webperftestharness.js"></script>
+<script src="resources/webperftestharnessextension.js"></script>
+
+<script>
+    setup({explicit_done: true});
+    function onload_test() {
+        const context = new PerformanceContext(performance);
+        const entry = context.getEntriesByName(document.getElementById('frameContext').src, 'resource')[0];
+
+        test_greater_than(entry.redirectStart, 0, 'redirectStart should be greater than 0 in timing allowed cross-origin redirect.');
+        test_equals(entry.redirectStart, entry.startTime, 'redirectStart should be equal to startTime in timing allowed cross-origin redirect.');
+        test_greater_or_equals(entry.redirectEnd, entry.redirectStart, 'redirectEnd should be no less than redirectStart in timing allowed cross-origin redirect.');
+        test_greater_or_equals(entry.fetchStart, entry.redirectEnd, 'fetchStart should be no less than redirectEnd in timing allowed cross-origin redirect.');
+        done();
+    }
+</script>
+
+</head>
+<body>
+<iframe id="frameContext" src="" style="width: 250px; height: 250px;"></iframe>
+<script>
+    const destUrl = '/common/redirect.py?location=/resource-timing/resources/iframe_TAO_match_origin.html';
+
+    const frameContext = document.getElementById('frameContext');
+    frameContext.onload = onload_test;
+    frameContext.src = destUrl;
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/resource-timing/resource_timing_buffer_full_when_populate_entries.html b/tests/wpt/web-platform-tests/resource-timing/resource_timing_buffer_full_when_populate_entries.html
new file mode 100644
index 00000000000..3e62b199a32
--- /dev/null
+++ b/tests/wpt/web-platform-tests/resource-timing/resource_timing_buffer_full_when_populate_entries.html
@@ -0,0 +1,41 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8" />
+<link rel="author" title="Intel" href="http://www.intel.com/" />
+<link rel="help" href="http://www.w3.org/TR/resource-timing/#performanceresourcetiming"/>
+<title>This test validates the functionality of onresourcetimingbufferfull in resource timing.</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/webperftestharness.js"></script>
+<script src="resources/webperftestharnessextension.js"></script>
+</head>
+<body onload=onload_test()>
+<script>
+    const context = new PerformanceContext(performance);
+    const bufferSize = 5;
+    context.setResourceTimingBufferSize(bufferSize);
+    let bufferFullCount = 0;
+    function buffer_full_callback() {
+        bufferFullCount++;
+    }
+    context.registerResourceTimingBufferFullCallback(buffer_full_callback);
+    // Scripts appended in JS to ensure setResourceTimingBufferSize is called before.
+    function appendScript(src) {
+        const script = document.createElement('script');
+        script.type = 'text/javascript';
+        script.src = src;
+        document.body.appendChild(script);
+    }
+    appendScript('resources/empty.js');
+    appendScript('resources/empty_script.js');
+    appendScript('resources/resource_timing_test0.js');
+    setup({ explicit_done: true });
+    function onload_test() {
+        test_equals(context.getEntriesByType('resource').length, bufferSize, 'There should only be |bufferSize| resource entries.');
+        test_equals(bufferFullCount, 1, 'onresourcetimingbufferfull should have been invoked once buffer is full.');
+        done();
+    }
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/resource-timing/resource_timing_buffer_full_when_shrink_buffer_size.html b/tests/wpt/web-platform-tests/resource-timing/resource_timing_buffer_full_when_shrink_buffer_size.html
new file mode 100644
index 00000000000..e42c19d05e0
--- /dev/null
+++ b/tests/wpt/web-platform-tests/resource-timing/resource_timing_buffer_full_when_shrink_buffer_size.html
@@ -0,0 +1,31 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8" />
+<title>This test validates the functionality of onresourcetimingbufferfull in resource timing.</title>
+<link rel="author" title="Intel" href="http://www.intel.com/" />
+<link rel="help" href="http://www.w3.org/TR/resource-timing/#performanceresourcetiming"/>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/webperftestharness.js"></script>
+<script src="resources/webperftestharnessextension.js"></script>
+<script>
+    const context = new PerformanceContext(performance);
+    let bufferFullCount = 0;
+    function buffer_full_call_back() {
+        bufferFullCount++;
+    }
+    context.registerResourceTimingBufferFullCallback(buffer_full_call_back);
+    setup({ explicit_done: true });
+    function onload_test() {
+        context.setResourceTimingBufferSize(3);
+        context.setResourceTimingBufferSize(0);
+        test_equals(context.getEntriesByType('resource').length, 4, 'There are 4 scripts, and setResourceTimingBufferSize does not reduce the size.');
+        test_equals(bufferFullCount, 0, 'onresourcetimingbufferfull should not be invoked during setResourceTimingBufferSize.');
+        done();
+    }
+</script>
+</head>
+<body onload=onload_test()>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/resource-timing/resource_timing_cross_origin_redirect.html b/tests/wpt/web-platform-tests/resource-timing/resource_timing_cross_origin_redirect.html
new file mode 100644
index 00000000000..9342f5b8838
--- /dev/null
+++ b/tests/wpt/web-platform-tests/resource-timing/resource_timing_cross_origin_redirect.html
@@ -0,0 +1,46 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8" />
+<title>This test validates the values in resource timing for a cross-origin redirect.</title>
+<link rel="author" title="Intel" href="http://www.intel.com/" />
+<link rel="help" href="http://www.w3.org/TR/resource-timing/#performanceresourcetiming"/>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/webperftestharness.js"></script>
+<script src="resources/webperftestharnessextension.js"></script>
+
+<script>
+    setup({explicit_done: true});
+    function onload_test() {
+        const context = new PerformanceContext(performance);
+        const entry = context.getEntriesByName(document.getElementById('frameContext').src, 'resource')[0];
+
+        test_equals(entry.redirectStart, 0, 'redirectStart should be 0 in cross-origin redirect.');
+        test_equals(entry.redirectEnd, 0, 'redirectEnd should be 0 in cross-origin redirect.');
+        test_equals(entry.domainLookupStart, 0, 'domainLookupStart should be 0 in cross-origin redirect.');
+        test_equals(entry.domainLookupEnd, 0, 'domainLookupEnd should be 0 in cross-origin redirect.');
+        test_equals(entry.connectStart, 0, 'connectStart should be 0 in cross-origin redirect.');
+        test_equals(entry.connectEnd, 0, 'connectEnd should be 0 in cross-origin redirect.');
+        test_equals(entry.requestStart, 0, 'requestStart should be 0 in cross-origin redirect.');
+        test_equals(entry.responseStart, 0, 'responseStart should be 0 in cross-origin redirect.');
+        test_equals(entry.secureConnectionStart, 0, 'secureConnectionStart should be 0 in cross-origin redirect.');
+        test_greater_than(entry.fetchStart, 0, 'fetchStart should be greater than 0 in cross-origin redirect.');
+        test_greater_than(entry.responseEnd, 0, 'responseEnd should be greater than 0 in cross-origin redirect.');
+        done();
+    }
+</script>
+</head>
+<body>
+<iframe id="frameContext" src="" style="width: 250px; height: 250px;"></iframe>
+<script>
+    let destUrl = '/common/redirect.py?location=';
+    // Add www to get a cross origin frame.
+    destUrl += 'http://www.' + document.location.host + '/resource-timing/resources/blank_page_green.htm';
+
+    const frameContext = document.getElementById('frameContext');
+    frameContext.onload = onload_test;
+    frameContext.src = destUrl;
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/resource-timing/resource_timing_same_origin_redirect.html b/tests/wpt/web-platform-tests/resource-timing/resource_timing_same_origin_redirect.html
new file mode 100644
index 00000000000..d9fbf944f6c
--- /dev/null
+++ b/tests/wpt/web-platform-tests/resource-timing/resource_timing_same_origin_redirect.html
@@ -0,0 +1,39 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8" />
+<title>This test validates the values of the redirectStart/End in resource timing for a same-origin resource redirect.</title>
+<link rel="author" title="Intel" href="http://www.intel.com/" />
+<link rel="help" href="http://www.w3.org/TR/resource-timing/#performanceresourcetiming"/>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/webperftestharness.js"></script>
+<script src="resources/webperftestharnessextension.js"></script>
+
+<script>
+    setup({explicit_done: true});
+    function onload_test() {
+        const context = new PerformanceContext(performance);
+        const entry = context.getEntriesByName(document.getElementById('frameContext').src, 'resource')[0];
+
+        test_greater_than(entry.redirectStart, 0, 'redirectStart should be greater than 0 in same-origin redirect.');
+        test_equals(entry.redirectStart, entry.startTime, 'redirectStart should be equal to startTime in same-origin redirect.');
+        test_noless_than(entry.redirectEnd, entry.redirectStart, 'redirectEnd should be no less than redirectStart in same-origin redirect.');
+        test_noless_than(entry.fetchStart, entry.redirectEnd, 'fetchStart should be no less than redirectEnd in same-origin redirect.');
+        done();
+    }
+</script>
+
+</head>
+<body>
+<iframe id="frameContext" src="" style="width: 250px; height: 250px;"></iframe>
+<script>
+    let destUrl = '/common/redirect.py';
+    destUrl += '?location=/resource-timing/resources/blank_page_green.htm';
+
+    const frameContext = document.getElementById('frameContext');
+    frameContext.onload = onload_test;
+    frameContext.src = destUrl;
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/resource-timing/resource_timing_store_and_clear_during_callback.html b/tests/wpt/web-platform-tests/resource-timing/resource_timing_store_and_clear_during_callback.html
new file mode 100644
index 00000000000..218fc0c2bcd
--- /dev/null
+++ b/tests/wpt/web-platform-tests/resource-timing/resource_timing_store_and_clear_during_callback.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<head onload>
+<meta charset="utf-8" />
+<title>This test validates the behavior of read and clear operation in onresourcetimingbufferfull callback of resource timing.</title>
+<link rel="author" title="Intel" href="http://www.intel.com/" />
+<link rel="help" href="http://www.w3.org/TR/resource-timing/#performanceresourcetiming"/>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/webperftestharness.js"></script>
+<script src="resources/webperftestharnessextension.js"></script>
+</head>
+<body onload=onload_test()>
+<script>
+    const context = new PerformanceContext(performance);
+    const resource_timing_buffer_size = 1;
+    let global_buffer = [];
+    function store_and_clear() {
+        const entryList = context.getEntriesByType('resource');
+        entryList.forEach(function (entry) {
+            global_buffer.push(entry);
+        });
+        context.clearResourceTimings();
+    }
+    context.registerResourceTimingBufferFullCallback(store_and_clear);
+    context.setResourceTimingBufferSize(resource_timing_buffer_size);
+    // Scripts appended in JS to ensure setResourceTimingBufferSize is called before.
+    function appendScript(src) {
+        const script = document.createElement('script');
+        script.type = 'text/javascript';
+        script.src = src;
+        document.body.appendChild(script);
+    }
+    appendScript('resources/empty.js');
+    appendScript('resources/empty_script.js');
+    appendScript('resources/resource_timing_test0.js');
+    setup({ explicit_done: true });
+    function onload_test() {
+        test_equals(context.getEntriesByType('resource').length, 0, 'No entry should be stored in resource timing buffer since its cleared once an item arrived.');
+        // The entry for empty.js must not be in the global buffer, but all others should be.
+        test_equals(global_buffer.length, 6, '6 resource timing entries should be moved to global buffer.');
+        const index = window.location.pathname.lastIndexOf('resource-timing');
+        const pathname = window.location.pathname.substring(0, index);
+        let expected_entries = {};
+        expected_entries[pathname + 'resources/testharness.js'] = 'script';
+        expected_entries[pathname + 'resources/testharnessreport.js'] = 'script';
+        expected_entries[pathname + 'resource-timing/resources/webperftestharness.js'] = 'script';
+        expected_entries[pathname + 'resource-timing/resources/webperftestharnessextension.js'] = 'script';
+        expected_entries[pathname + 'resource-timing/resources/empty_script.js'] = 'script';
+        expected_entries[pathname + 'resource-timing/resources/resource_timing_test0.js'] = 'script';
+        test_resource_entries(global_buffer, expected_entries);
+        done();
+    }
+</script>
+</body>
+</html>
diff --git a/tests/wpt/web-platform-tests/service-workers/cache-storage/script-tests/cache-put.js b/tests/wpt/web-platform-tests/service-workers/cache-storage/script-tests/cache-put.js
index 467e0b38e9c..38d25647b34 100644
--- a/tests/wpt/web-platform-tests/service-workers/cache-storage/script-tests/cache-put.js
+++ b/tests/wpt/web-platform-tests/service-workers/cache-storage/script-tests/cache-put.js
@@ -335,4 +335,12 @@ cache_test(function(cache) {
         });
   }, 'Cache.put should store Response.redirect() correctly');
 
+cache_test(async (cache) => {
+    var request = new Request(test_url);
+    var response = new Response(new Blob([test_body]));
+    await cache.put(request, response);
+    var cachedResponse = await cache.match(request);
+    assert_equals(await cachedResponse.text(), test_body);
+  }, 'Cache.put called with simple Request and blob Response');
+
 done();
diff --git a/tests/wpt/web-platform-tests/service-workers/cache-storage/window/cache-put.https.html b/tests/wpt/web-platform-tests/service-workers/cache-storage/window/cache-put.https.html
index ded6e84cb53..1ee14bdd124 100644
--- a/tests/wpt/web-platform-tests/service-workers/cache-storage/window/cache-put.https.html
+++ b/tests/wpt/web-platform-tests/service-workers/cache-storage/window/cache-put.https.html
@@ -6,3 +6,16 @@
 <script src="/resources/testharnessreport.js"></script>
 <script src="../resources/test-helpers.js"></script>
 <script src="../script-tests/cache-put.js"></script>
+<script>
+cache_test(async (cache) => {
+    var formData = new FormData();
+    formData.append("name", "value");
+
+    var request = new Request(test_url);
+    var response = new Response(formData);
+    await cache.put(request, response);
+    var cachedResponse = await cache.match(request);
+    var cachedResponseText = await cachedResponse.text();
+    assert_true(cachedResponseText.indexOf("name=\"name\"\r\n\r\nvalue") !== -1);
+  }, 'Cache.put called with simple Request and form data Response');
+</script>
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/resources/vtt-frame.html b/tests/wpt/web-platform-tests/service-workers/service-worker/resources/vtt-frame.html
new file mode 100644
index 00000000000..c3ac8034e19
--- /dev/null
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/resources/vtt-frame.html
@@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Page Title</title>
+<video>
+  <track>
+</video>
diff --git a/tests/wpt/web-platform-tests/service-workers/service-worker/webvtt-cross-origin.https.html b/tests/wpt/web-platform-tests/service-workers/service-worker/webvtt-cross-origin.https.html
new file mode 100644
index 00000000000..0f980607bab
--- /dev/null
+++ b/tests/wpt/web-platform-tests/service-workers/service-worker/webvtt-cross-origin.https.html
@@ -0,0 +1,106 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>cross-origin webvtt returned by service worker is detected</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/get-host-info.sub.js"></script>
+<script src="resources/test-helpers.sub.js?pipe=sub"></script>
+<body>
+<script>
+// This file tests opaque responses for WebVTT text track. It creates
+// an iframe with a <track> element, controlled by a service worker.
+// Each test tries to load a text track, the service worker intercepts the
+// requests and responds with opaque or non-opaque responses. The opaque
+// responses should result in load errors.
+
+const host_info = get_host_info();
+const kScript = 'resources/fetch-rewrite-worker.js';
+// Add '?ignore' so the service worker falls back for the navigation.
+const kScope = 'resources/vtt-frame.html?ignore';
+let frame;
+
+function load_track(url) {
+  const track = frame.contentDocument.querySelector('track');
+  const result = new Promise((resolve, reject) => {
+      track.onload = (e => {
+          resolve('load event');
+        });
+      track.onerror = (e => {
+          resolve('error event');
+        });
+    });
+
+  track.src = url;
+  // Setting mode to hidden seems needed, or else the text track requests don't
+  // occur.
+  track.track.mode = 'hidden';
+  return result;
+}
+
+promise_test(t => {
+    return service_worker_unregister_and_register(t, kScript, kScope)
+      .then(registration => {
+          promise_test(() => {
+              frame.remove();
+              return registration.unregister();
+            }, 'restore global state');
+
+          return wait_for_state(t, registration.installing, 'activated');
+        })
+      .then(() => {
+          return with_iframe(kScope);
+        })
+      .then(f => {
+          frame = f;
+        })
+  }, 'initialize global state');
+
+promise_test(t => {
+    let url = '/media/foo.vtt';
+    // Add '?url' and tell the service worker to return a same-origin URL.
+    url += '?url=' + host_info.HTTPS_ORIGIN + '/media/foo.vtt';
+    return load_track(url)
+      .then(result => {
+          assert_equals(result, 'load event');
+        });
+  }, 'same-origin text track should load');
+
+promise_test(t => {
+    let url = '/media/foo.vtt';
+    // Add '?url' and tell the service worker to return a cross-origin URL.
+    url += '?url=' + get_host_info().HTTPS_REMOTE_ORIGIN + '/media/foo.vtt';
+    return load_track(url)
+      .then(result => {
+          assert_equals(result, 'error event');
+        });
+  }, 'cross-origin text track with no-cors request should not load');
+
+promise_test(t => {
+    let url = '/media/foo.vtt';
+    // Add '?url' and tell the service worker to return a cross-origin URL that
+    // doesn't support CORS.
+    url += '?url=' + get_host_info().HTTPS_REMOTE_ORIGIN +
+        '/media/foo-no-cors.vtt';
+    // Add '&mode' to tell the service worker to do a CORS request.
+    url += '&mode=cors';
+    return load_track(url)
+      .then(result => {
+          assert_equals(result, 'error event');
+        });
+  }, 'cross-origin text track with rejected cors request should not load');
+
+promise_test(t => {
+    let url = '/media/foo.vtt';
+    // Add '?url' and tell the service worker to return a cross-origin URL.
+    url += '?url=' + get_host_info().HTTPS_REMOTE_ORIGIN + '/media/foo.vtt';
+    // Add '&mode' to tell the service worker to do a CORS request.
+    url += '&mode=cors';
+    // Add '&credentials=anonymous' to allow Access-Control-Allow-Origin=*.
+    url += '&credentials=anonymous';
+    return load_track(url)
+      .then(result => {
+          assert_equals(result, 'load event');
+        });
+  }, 'cross-origin text track with approved cors request should load');
+</script>
+</body>
diff --git a/tests/wpt/web-platform-tests/streams/readable-byte-streams/properties.js b/tests/wpt/web-platform-tests/streams/readable-byte-streams/properties.js
index 02d029431ae..975fba7109b 100644
--- a/tests/wpt/web-platform-tests/streams/readable-byte-streams/properties.js
+++ b/tests/wpt/web-platform-tests/streams/readable-byte-streams/properties.js
@@ -88,7 +88,7 @@ promise_test(t => {
         assert_not_equals(viewPropDesc.get, undefined, 'view should have a getter');
         assert_equals(viewPropDesc.set, undefined, 'view should not have a setter');
         assert_not_equals(byobRequest.view, undefined, 'has a non-undefined view property');
-        assert_equals(byobRequest.constructor.length, 2, 'constructor has 1 parameter');
+        assert_equals(byobRequest.constructor.length, 0, 'constructor has 0 parameters');
         assert_equals(byobRequest.respond.length, 1, 'respond has 1 parameter');
         assert_equals(byobRequest.respondWithNewView.length, 1, 'releaseLock has 1 parameter');
 
diff --git a/tests/wpt/web-platform-tests/tools/ci/commands.json b/tests/wpt/web-platform-tests/tools/ci/commands.json
index d682d2a5064..a8db428e28f 100644
--- a/tests/wpt/web-platform-tests/tools/ci/commands.json
+++ b/tests/wpt/web-platform-tests/tools/ci/commands.json
@@ -2,5 +2,6 @@
     "test-jobs": {"path": "jobs.py", "script": "run", "parser": "create_parser", "help": "List test jobs that should run for a set of commits",
                   "virtualenv": false},
     "check-stability": {"path": "check_stability.py", "script": "run", "parser": "get_parser", "parse_known": true, "help": "Check test stability",
-                        "virtualenv": true, "install": ["requests"], "requirements": ["../wptrunner/requirements.txt"]}
+                        "virtualenv": true, "install": ["requests"], "requirements": ["../wptrunner/requirements.txt"]},
+  "make-hosts-file": {"path": "make_hosts_file.py", "script": "run", "parser": "create_parser", "help": "Output a hosts file to stdout", "virtualenv": false}
 }
diff --git a/tests/wpt/web-platform-tests/tools/ci/lib.sh b/tests/wpt/web-platform-tests/tools/ci/lib.sh
index db49ec6b449..2273793ba32 100644
--- a/tests/wpt/web-platform-tests/tools/ci/lib.sh
+++ b/tests/wpt/web-platform-tests/tools/ci/lib.sh
@@ -6,15 +6,7 @@ hosts_fixup() {
     echo "## /etc/hosts ##"
     cat /etc/hosts
     sudo sed -i 's/^::1\s*localhost/::1/' /etc/hosts
-    sudo sh -c 'echo "
-127.0.0.1 web-platform.test
-127.0.0.1 www.web-platform.test
-127.0.0.1 www1.web-platform.test
-127.0.0.1 www2.web-platform.test
-127.0.0.1 xn--n8j6ds53lwwkrqhv28a.web-platform.test
-127.0.0.1 xn--lve-6lad.web-platform.test
-0.0.0.0 nonexistent-origin.web-platform.test
-" >> /etc/hosts'
+    ./wpt make-hosts-file | sudo tee -a /etc/hosts
     echo "== /etc/hosts =="
     cat /etc/hosts
     echo "----------------"
diff --git a/tests/wpt/web-platform-tests/tools/ci/make_hosts_file.py b/tests/wpt/web-platform-tests/tools/ci/make_hosts_file.py
new file mode 100644
index 00000000000..b3c7758b2ac
--- /dev/null
+++ b/tests/wpt/web-platform-tests/tools/ci/make_hosts_file.py
@@ -0,0 +1,19 @@
+import argparse
+import os
+
+from ..localpaths import repo_root
+
+from ..serve.serve import load_config, normalise_config, make_hosts_file
+
+def create_parser():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("address", default="127.0.0.1", nargs="?", help="Address that hosts should point at")
+    return parser
+
+def run(**kwargs):
+    config = load_config(os.path.join(repo_root, "config.default.json"),
+                         os.path.join(repo_root, "config.json"))
+
+    config = normalise_config(config, {})
+
+    print(make_hosts_file(config, kwargs["address"]))
diff --git a/tests/wpt/web-platform-tests/tools/conftest.py b/tests/wpt/web-platform-tests/tools/conftest.py
index 894fe6223ea..4ce5e74b06e 100644
--- a/tests/wpt/web-platform-tests/tools/conftest.py
+++ b/tests/wpt/web-platform-tests/tools/conftest.py
@@ -1,5 +1,6 @@
 import platform
 import os
+import sys
 
 from hypothesis import settings, HealthCheck
 
@@ -11,3 +12,11 @@ settings.register_profile("pypy", settings(suppress_health_check=[HealthCheck.to
 
 settings.load_profile(os.getenv("HYPOTHESIS_PROFILE",
                                 "default" if impl != "PyPy" else "pypy"))
+
+# serve can't even be imported on Py3, so totally ignore it even from collection
+collect_ignore = []
+if sys.version_info[0] >= 3:
+    serve = os.path.join(os.path.dirname(__file__), "serve")
+    collect_ignore.extend([os.path.join(root, f)
+                           for root, _, files in os.walk(serve)
+                           for f in files])
diff --git a/tests/wpt/web-platform-tests/tools/serve/serve.py b/tests/wpt/web-platform-tests/tools/serve/serve.py
index c77badc2682..9c5e7ca413f 100644
--- a/tests/wpt/web-platform-tests/tools/serve/serve.py
+++ b/tests/wpt/web-platform-tests/tools/serve/serve.py
@@ -203,6 +203,8 @@ subdomains = [u"www",
               u"天気の良い日",
               u"élève"]
 
+not_subdomains = [u"nonexistent-origin"]
+
 class RoutesBuilder(object):
     def __init__(self):
         self.forbidden_override = [("GET", "/tools/runner/*", handlers.file_handler),
@@ -468,6 +470,24 @@ def get_subdomains(host):
             for subdomain in subdomains}
 
 
+def get_not_subdomains(host):
+    #This assumes that the tld is ascii-only or already in punycode
+    return {subdomain: (subdomain.encode("idna"), host)
+            for subdomain in not_subdomains}
+
+
+def make_hosts_file(config, host):
+    rv = []
+
+    for domain in config["domains"].values():
+        rv.append("%s\t%s\n" % (host, domain))
+
+    for not_domain in config.get("not_domains", {}).values():
+        rv.append("0.0.0.0\t%s\n" % not_domain)
+
+    return "".join(rv)
+
+
 def start_servers(host, ports, paths, routes, bind_hostname, config, ssl_config,
                   **kwargs):
     servers = defaultdict(list)
@@ -626,6 +646,7 @@ def get_ports(config, ssl_environment):
 def normalise_config(config, ports):
     host = config["external_host"] if config["external_host"] else config["host"]
     domains = get_subdomains(host)
+    not_domains = get_not_subdomains(host)
     ports_ = {}
     for scheme, ports_used in ports.iteritems():
         ports_[scheme] = ports_used
@@ -633,6 +654,9 @@ def normalise_config(config, ports):
     for key, value in domains.iteritems():
         domains[key] = ".".join(value)
 
+    for key, value in not_domains.iteritems():
+        not_domains[key] = ".".join(value)
+
     domains[""] = host
 
     ports_ = {}
@@ -644,6 +668,7 @@ def normalise_config(config, ports):
     config_ = config.copy()
     config_["host"] = host
     config_["domains"] = domains
+    config_["not_domains"] = not_domains
     config_["ports"] = ports_
     return config_
 
diff --git a/tests/wpt/web-platform-tests/tools/serve/test_serve.py b/tests/wpt/web-platform-tests/tools/serve/test_serve.py
new file mode 100644
index 00000000000..333760153e9
--- /dev/null
+++ b/tests/wpt/web-platform-tests/tools/serve/test_serve.py
@@ -0,0 +1,12 @@
+from . import serve
+
+def test_make_hosts_file():
+    hosts = serve.make_hosts_file({
+        "domains": {"www": "www.foo.bar.test", "www1": "www1.foo.bar.test"},
+        "not_domains": {"aaa": "aaa.foo.bar.test", "bbb": "bbb.foo.bar.test"}
+    }, "127.1.1.1")
+    lines = hosts.split("\n")
+    assert "127.1.1.1\twww.foo.bar.test" in lines
+    assert "127.1.1.1\twww1.foo.bar.test" in lines
+    assert "0.0.0.0\taaa.foo.bar.test" in lines
+    assert "0.0.0.0\tbbb.foo.bar.test" in lines
diff --git a/tests/wpt/web-platform-tests/tools/wpt/run.py b/tests/wpt/web-platform-tests/tools/wpt/run.py
index f3fbcbdefb0..236299e2a73 100644
--- a/tests/wpt/web-platform-tests/tools/wpt/run.py
+++ b/tests/wpt/web-platform-tests/tools/wpt/run.py
@@ -11,6 +11,8 @@ wpt_root = os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir, os
 sys.path.insert(0, os.path.abspath(os.path.join(wpt_root, "tools")))
 
 from . import browser, utils, virtualenv
+from ..serve import serve
+
 logger = None
 
 
@@ -94,13 +96,10 @@ otherwise install OpenSSL and ensure that it's on your $PATH.""")
 
 def check_environ(product):
     if product not in ("firefox", "servo"):
-        expected_hosts = ["web-platform.test",
-                          "www.web-platform.test",
-                          "www1.web-platform.test",
-                          "www2.web-platform.test",
-                          "xn--n8j6ds53lwwkrqhv28a.web-platform.test",
-                          "xn--lve-6lad.web-platform.test",
-                          "nonexistent-origin.web-platform.test"]
+        expected_hosts = {".".join(x)
+                          for x in serve.get_subdomains("web-platform.test").values()}
+        expected_hosts |= {".".join(x)
+                           for x in serve.get_not_subdomains("web-platform.test").values()}
         missing_hosts = set(expected_hosts)
         if platform.uname()[0] != "Windows":
             hosts_path = "/etc/hosts"
@@ -114,13 +113,17 @@ def check_environ(product):
                 for host in hosts:
                     missing_hosts.discard(host)
             if missing_hosts:
-                raise WptrunError("""Missing hosts file configuration. Expected entries like:
+                if platform.uname()[0] != "Windows":
+                    message = """Missing hosts file configuration. Run
 
-%s
+python wpt make-hosts-file >> %s
 
-See README.md for more details.""" % "\n".join("%s\t%s" %
-                                               ("127.0.0.1" if "nonexistent" not in host else "0.0.0.0", host)
-                                               for host in expected_hosts))
+from a shell with Administrator privileges.""" % hosts_path
+                else:
+                    message = """Missing hosts file configuration. Run
+
+./wpt make-hosts-file | sudo tee -a %s""" % hosts_path
+                raise WptrunError(message)
 
 
 class BrowserSetup(object):
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/MANIFEST.in b/tests/wpt/web-platform-tests/tools/wptrunner/MANIFEST.in
index 70839237889..d3b530a500b 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/MANIFEST.in
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/MANIFEST.in
@@ -5,4 +5,3 @@ include wptrunner/testharness_runner.html
 include wptrunner/*.js
 include wptrunner/executors/*.js
 include wptrunner/config.json
-include wptrunner/browsers/server-locations.txt
\ No newline at end of file
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/setup.py b/tests/wpt/web-platform-tests/tools/wptrunner/setup.py
index 7da51418327..148a1d2f8c1 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/setup.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/setup.py
@@ -52,7 +52,6 @@ setup(name=PACKAGE_NAME,
                                   "testharness_runner.html",
                                   "config.json",
                                   "wptrunner.default.ini",
-                                  "browsers/server-locations.txt",
                                   "browsers/sauce_setup/*",
                                   "prefs/*"]},
       include_package_data=True,
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/chrome.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/chrome.py
index 215fccffe2a..7f9a21cb44b 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/chrome.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/chrome.py
@@ -60,8 +60,7 @@ def env_extras(**kwargs):
 
 
 def env_options():
-    return {"host": "web-platform.test",
-            "bind_hostname": "true"}
+    return {"bind_hostname": "true"}
 
 
 class ChromeBrowser(Browser):
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/chrome_android.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/chrome_android.py
index 47090be0439..3e832cbd716 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/chrome_android.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/chrome_android.py
@@ -68,8 +68,7 @@ def env_extras(**kwargs):
 
 
 def env_options():
-    return {"host": "web-platform.test",
-            "bind_hostname": "true"}
+    return {"bind_hostname": "true"}
 
 
 class ChromeAndroidBrowser(Browser):
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/edge.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/edge.py
index db4ae005e90..094405c61c2 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/edge.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/edge.py
@@ -38,8 +38,7 @@ def env_extras(**kwargs):
     return []
 
 def env_options():
-    return {"host": "web-platform.test",
-            "bind_hostname": "true",
+    return {"bind_hostname": "true",
             "supports_debugger": False}
 
 class EdgeBrowser(Browser):
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 6d1f58d3791..57e05278c0a 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
@@ -3,12 +3,12 @@ import platform
 import signal
 import subprocess
 import sys
+import tempfile
 
 import mozinfo
 import mozleak
 from mozprocess import ProcessHandler
 from mozprofile import FirefoxProfile, Preferences
-from mozprofile.permissions import ServerLocations
 from mozrunner import FirefoxRunner
 from mozrunner.utils import get_stack_fixer_function
 from mozcrash import mozcrash
@@ -23,7 +23,6 @@ from ..executors import executor_kwargs as base_executor_kwargs
 from ..executors.executormarionette import (MarionetteTestharnessExecutor,
                                             MarionetteRefTestExecutor,
                                             MarionetteWdspecExecutor)
-from ..environment import hostnames
 
 
 here = os.path.join(os.path.split(__file__)[0])
@@ -80,7 +79,8 @@ def browser_kwargs(test_type, run_info_data, **kwargs):
                                                          **kwargs),
             "leak_check": kwargs["leak_check"],
             "stylo_threads": kwargs["stylo_threads"],
-            "chaos_mode_flags": kwargs["chaos_mode_flags"]}
+            "chaos_mode_flags": kwargs["chaos_mode_flags"],
+            "config": kwargs["config"]}
 
 
 def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
@@ -102,7 +102,7 @@ def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
         if kwargs["binary_args"]:
             options["args"] = kwargs["binary_args"]
         options["prefs"] = {
-            "network.dns.localDomains": ",".join(hostnames)
+            "network.dns.localDomains": ",".join(server_config['domains'].values())
         }
         capabilities["moz:firefoxOptions"] = options
     if kwargs["certutil_binary"] is None:
@@ -143,7 +143,7 @@ class FirefoxBrowser(Browser):
                  symbols_path=None, stackwalk_binary=None, certutil_binary=None,
                  ca_certificate_path=None, e10s=False, stackfix_dir=None,
                  binary_args=None, timeout_multiplier=None, leak_check=False, stylo_threads=1,
-                 chaos_mode_flags=None):
+                 chaos_mode_flags=None, config=None):
         Browser.__init__(self, logger)
         self.binary = binary
         self.prefs_root = prefs_root
@@ -159,6 +159,7 @@ class FirefoxBrowser(Browser):
         self.certutil_binary = certutil_binary
         self.e10s = e10s
         self.binary_args = binary_args
+        self.config = config
         if stackfix_dir:
             self.stack_fixer = get_stack_fixer_function(stackfix_dir,
                                                         self.symbols_path)
@@ -189,15 +190,12 @@ class FirefoxBrowser(Browser):
         if self.chaos_mode_flags is not None:
             env["MOZ_CHAOSMODE"] = str(self.chaos_mode_flags)
 
-        locations = ServerLocations(filename=os.path.join(here, "server-locations.txt"))
-
         preferences = self.load_prefs()
 
-        self.profile = FirefoxProfile(locations=locations,
-                                      preferences=preferences)
+        self.profile = FirefoxProfile(preferences=preferences)
         self.profile.set_preferences({"marionette.port": self.marionette_port,
                                       "dom.disable_open_during_load": False,
-                                      "network.dns.localDomains": ",".join(hostnames),
+                                      "network.dns.localDomains": ",".join(self.config['domains'].values()),
                                       "network.proxy.type": 0,
                                       "places.history.enabled": False,
                                       "dom.send_after_paint_to_content": True,
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/ie.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/ie.py
index 13f5827194d..9c0007e4630 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/ie.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/ie.py
@@ -42,8 +42,7 @@ def env_extras(**kwargs):
     return []
 
 def env_options():
-    return {"host": "web-platform.test",
-            "bind_hostname": "true",
+    return {"bind_hostname": "true",
             "supports_debugger": False}
 
 class InternetExplorerBrowser(Browser):
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/opera.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/opera.py
index 57edfa06bd5..693a19ac24c 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/opera.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/opera.py
@@ -60,8 +60,7 @@ def env_extras(**kwargs):
 
 
 def env_options():
-    return {"host": "web-platform.test",
-            "bind_hostname": "true"}
+    return {"bind_hostname": "true"}
 
 
 class OperaBrowser(Browser):
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/sauce.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/sauce.py
index 4c1be1c0e22..42c83c5d24f 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/sauce.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/sauce.py
@@ -113,8 +113,7 @@ def env_extras(**kwargs):
 
 
 def env_options():
-    return {"host": "web-platform.test",
-            "bind_hostname": "true",
+    return {"bind_hostname": "true",
             "supports_debugger": False}
 
 
@@ -128,6 +127,7 @@ def get_tar(url, dest):
 class SauceConnect():
 
     def __init__(self, **kwargs):
+        self.config = kwargs["config"]
         self.sauce_user = kwargs["sauce_user"]
         self.sauce_key = kwargs["sauce_key"]
         self.sauce_tunnel_id = kwargs["sauce_tunnel_id"]
@@ -153,8 +153,7 @@ class SauceConnect():
             "--metrics-address=0.0.0.0:9876",
             "--readyfile=./sauce_is_ready",
             "--tunnel-domains",
-            "web-platform.test",
-            "*.web-platform.test"
+            ",".join(self.config['domains'].values())
         ])
 
         # Timeout config vars
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/server-locations.txt b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/server-locations.txt
deleted file mode 100644
index 5dcaf4bb6a4..00000000000
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/server-locations.txt
+++ /dev/null
@@ -1,31 +0,0 @@
-http://localhost:8000    primary
-
-http://web-platform.test:8000
-http://www.web-platform.test:8000
-http://www1.web-platform.test:8000
-http://www2.web-platform.test:8000
-http://xn--n8j6ds53lwwkrqhv28a.web-platform.test:8000
-http://xn--lve-6lad.web-platform.test:8000
-
-http://web-platform.test:8001
-http://www.web-platform.test:8001
-http://www1.web-platform.test:8001
-http://www2.web-platform.test:8001
-http://xn--n8j6ds53lwwkrqhv28a.web-platform.test:8001
-http://xn--lve-6lad.web-platform.test:8001
-
-https://web-platform.test:8443
-https://www.web-platform.test:8443
-https://www1.web-platform.test:8443
-https://www2.web-platform.test:8443
-https://xn--n8j6ds53lwwkrqhv28a.web-platform.test:8443
-https://xn--lve-6lad.web-platform.test:8443
-
-# These are actually ws servers, but until mozprofile is
-# fixed we have to pretend that they are http servers
-http://web-platform.test:8888
-http://www.web-platform.test:8888
-http://www1.web-platform.test:8888
-http://www2.web-platform.test:8888
-http://xn--n8j6ds53lwwkrqhv28a.web-platform.test:8888
-http://xn--lve-6lad.web-platform.test:8888
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py
index c251de84d16..89504b21c88 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py
@@ -1,9 +1,12 @@
 import os
+import shutil
 import subprocess
 import tempfile
 
 from mozprocess import ProcessHandler
 
+from tools.serve.serve import make_hosts_file
+
 from .base import Browser, require_arg, get_free_port, browser_command, ExecutorBrowser
 from ..executors import executor_kwargs as base_executor_kwargs
 from ..executors.executorservodriver import (ServoWebDriverTestharnessExecutor,
@@ -26,14 +29,6 @@ __wptrunner__ = {
     "update_properties": "update_properties",
 }
 
-hosts_text = """127.0.0.1 web-platform.test
-127.0.0.1 www.web-platform.test
-127.0.0.1 www1.web-platform.test
-127.0.0.1 www2.web-platform.test
-127.0.0.1 xn--n8j6ds53lwwkrqhv28a.web-platform.test
-127.0.0.1 xn--lve-6lad.web-platform.test
-"""
-
 
 def check_args(**kwargs):
     require_arg(kwargs, "binary")
@@ -69,10 +64,10 @@ def update_properties():
     return ["debug", "os", "version", "processor", "bits"], None
 
 
-def make_hosts_file():
+def write_hosts_file(config):
     hosts_fd, hosts_path = tempfile.mkstemp()
     with os.fdopen(hosts_fd, "w") as f:
-        f.write(hosts_text)
+        f.write(make_hosts_file(config, "127.0.0.1"))
     return hosts_path
 
 
@@ -87,7 +82,7 @@ class ServoWebDriverBrowser(Browser):
         self.webdriver_port = None
         self.proc = None
         self.debug_info = debug_info
-        self.hosts_path = make_hosts_file()
+        self.hosts_path = write_hosts_file()
         self.command = None
         self.user_stylesheets = user_stylesheets if user_stylesheets else []
 
@@ -158,6 +153,7 @@ class ServoWebDriverBrowser(Browser):
 
     def cleanup(self):
         self.stop()
+        shutil.rmtree(os.path.dirname(self.hosts_file))
 
     def executor_browser(self):
         assert self.webdriver_port is not None
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/environment.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/environment.py
index 711534180dc..22b02a9e4ad 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/environment.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/environment.py
@@ -18,14 +18,6 @@ serve = None
 sslutils = None
 
 
-hostnames = ["web-platform.test",
-             "www.web-platform.test",
-             "www1.web-platform.test",
-             "www2.web-platform.test",
-             "xn--n8j6ds53lwwkrqhv28a.web-platform.test",
-             "xn--lve-6lad.web-platform.test"]
-
-
 def do_delayed_imports(logger, test_paths):
     global serve, sslutils
 
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservo.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservo.py
index ca8ec8a7eb5..3cf402d481f 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservo.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservo.py
@@ -13,6 +13,8 @@ from collections import defaultdict
 
 from mozprocess import ProcessHandler
 
+from tools.serve.serve import make_hosts_file
+
 from .base import (ExecutorException,
                    Protocol,
                    RefTestImplementation,
@@ -30,18 +32,10 @@ webdriver = None
 
 extra_timeout = 5  # seconds
 
-hosts_text = """127.0.0.1 web-platform.test
-127.0.0.1 www.web-platform.test
-127.0.0.1 www1.web-platform.test
-127.0.0.1 www2.web-platform.test
-127.0.0.1 xn--n8j6ds53lwwkrqhv28a.web-platform.test
-127.0.0.1 xn--lve-6lad.web-platform.test
-"""
-
-def make_hosts_file():
+def write_hosts_file(config):
     hosts_fd, hosts_path = tempfile.mkstemp()
     with os.fdopen(hosts_fd, "w") as f:
-        f.write(hosts_text)
+        f.write(make_hosts_file(config, "127.0.0.1"))
     return hosts_path
 
 
@@ -57,7 +51,7 @@ class ServoTestharnessExecutor(ProcessTestExecutor):
         self.result_data = None
         self.result_flag = None
         self.protocol = Protocol(self, browser)
-        self.hosts_path = make_hosts_file()
+        self.hosts_path = write_hosts_file(server_config)
 
     def teardown(self):
         try:
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/hosts.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/hosts.py
deleted file mode 100644
index 915c17f1b31..00000000000
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/hosts.py
+++ /dev/null
@@ -1,100 +0,0 @@
-from __future__ import unicode_literals
-
-
-class HostsLine(object):
-    def __init__(self, ip_address, canonical_hostname, aliases=None, comment=None):
-        self.ip_address = ip_address
-        self.canonical_hostname = canonical_hostname
-        self.aliases = aliases if aliases is not None else []
-        self.comment = comment
-        if self.ip_address is None:
-            assert self.canonical_hostname is None
-            assert not self.aliases
-            assert self.comment is not None
-
-    @classmethod
-    def from_string(cls, line):
-        if not line.strip():
-            return
-
-        line = line.strip()
-
-        ip_address = None
-        canonical_hostname = None
-        aliases = []
-        comment = None
-
-        comment_parts = line.split("#", 1)
-        if len(comment_parts) > 1:
-            comment = comment_parts[1]
-
-        data = comment_parts[0].strip()
-
-        if data:
-            fields = data.split()
-            if len(fields) < 2:
-                raise ValueError("Invalid hosts line")
-
-            ip_address = fields[0]
-            canonical_hostname = fields[1]
-            aliases = fields[2:]
-
-        return cls(ip_address, canonical_hostname, aliases, comment)
-
-
-class HostsFile(object):
-    def __init__(self):
-        self.data = []
-        self.by_hostname = {}
-
-    def set_host(self, host):
-        if host.canonical_hostname is None:
-            self.data.append(host)
-        elif host.canonical_hostname in self.by_hostname:
-            old_host = self.by_hostname[host.canonical_hostname]
-            old_host.ip_address = host.ip_address
-            old_host.aliases = host.aliases
-            old_host.comment = host.comment
-        else:
-            self.data.append(host)
-            self.by_hostname[host.canonical_hostname] = host
-
-    @classmethod
-    def from_file(cls, f):
-        rv = cls()
-        for line in f:
-            host = HostsLine.from_string(line)
-            if host is not None:
-                rv.set_host(host)
-        return rv
-
-    def to_string(self):
-        field_widths = [0, 0]
-        for line in self.data:
-            if line.ip_address is not None:
-                field_widths[0] = max(field_widths[0], len(line.ip_address))
-                field_widths[1] = max(field_widths[1], len(line.canonical_hostname))
-
-        lines = []
-
-        for host in self.data:
-            line = ""
-            if host.ip_address is not None:
-                ip_string = host.ip_address.ljust(field_widths[0])
-                hostname_str = host.canonical_hostname
-                if host.aliases:
-                    hostname_str = "%s %s" % (hostname_str.ljust(field_widths[1]),
-                                              " ".join(host.aliases))
-                line = "%s %s" % (ip_string, hostname_str)
-            if host.comment:
-                if line:
-                    line += " "
-                line += "#%s" % host.comment
-            lines.append(line)
-
-        lines.append("")
-
-        return "\n".join(lines)
-
-    def to_file(self, f):
-        f.write(self.to_string().encode("utf8"))
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/tests/browsers/__init__.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/tests/browsers/__init__.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/tests/browsers/test_sauce.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/tests/browsers/test_sauce.py
index bf3e487bd72..019b538ec1c 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/tests/browsers/test_sauce.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/tests/browsers/test_sauce.py
@@ -20,6 +20,9 @@ def test_sauceconnect_success():
         exists.return_value = True
 
         sauce_connect = sauce.SauceConnect(
+            config={
+                "domains": {"": "example.net"}
+            },
             sauce_user="aaa",
             sauce_key="bbb",
             sauce_tunnel_id="ccc",
@@ -46,6 +49,9 @@ def test_sauceconnect_failure_exit(readyfile, returncode):
         exists.return_value = readyfile
 
         sauce_connect = sauce.SauceConnect(
+            config={
+                "domains": {"": "example.net"}
+            },
             sauce_user="aaa",
             sauce_key="bbb",
             sauce_tunnel_id="ccc",
@@ -68,6 +74,9 @@ def test_sauceconnect_failure_never_ready():
         exists.return_value = False
 
         sauce_connect = sauce.SauceConnect(
+            config={
+                "domains": {"": "example.net"}
+            },
             sauce_user="aaa",
             sauce_key="bbb",
             sauce_tunnel_id="ccc",
@@ -82,3 +91,34 @@ def test_sauceconnect_failure_never_ready():
         # Check we actually kill it after termination fails
         Popen.return_value.terminate.assert_called()
         Popen.return_value.kill.assert_called()
+
+
+def test_sauceconnect_tunnel_domains():
+    with mock.patch.object(sauce.SauceConnect, "upload_prerun_exec"),\
+            mock.patch.object(sauce.subprocess, "Popen") as Popen,\
+            mock.patch.object(sauce.os.path, "exists") as exists:
+        Popen.return_value.poll.return_value = None
+        Popen.return_value.returncode = None
+        exists.return_value = True
+
+        sauce_connect = sauce.SauceConnect(
+            config={
+                "domains": {"foo": "foo.bar.example.com", "": "example.net"}
+            },
+            sauce_user="aaa",
+            sauce_key="bbb",
+            sauce_tunnel_id="ccc",
+            sauce_connect_binary="ddd")
+
+        sauce_connect.__enter__(None)
+
+        Popen.assert_called_once()
+        args, kwargs = Popen.call_args
+        cmd = args[0]
+        assert "--tunnel-domains" in cmd
+        i = cmd.index("--tunnel-domains")
+        rest = cmd[i+1:]
+        assert len(rest) >= 1
+        if len(rest) > 1:
+            assert rest[1].startswith("-"), "--tunnel-domains takes a comma separated list (not a space separated list)"
+        assert set(rest[0].split(",")) == {"foo.bar.example.com", "example.net"}
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/tests/test_hosts.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/tests/test_hosts.py
deleted file mode 100644
index e7d41f3b420..00000000000
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/tests/test_hosts.py
+++ /dev/null
@@ -1,54 +0,0 @@
-import unittest
-import sys
-from os.path import join, dirname
-from cStringIO import StringIO
-
-sys.path.insert(0, join(dirname(__file__), "..", ".."))
-
-from wptrunner import hosts
-
-
-class HostsTest(unittest.TestCase):
-    def do_test(self, input, expected):
-        host_file = hosts.HostsFile.from_file(StringIO(input))
-        self.assertEquals(host_file.to_string(), expected)
-
-    def test_simple(self):
-        self.do_test("""127.0.0.1    \tlocalhost  alias # comment
-# Another comment""",
-                     """127.0.0.1 localhost alias # comment
-# Another comment
-""")
-
-    def test_blank_lines(self):
-        self.do_test("""127.0.0.1    \tlocalhost  alias # comment
-
-\r
-    \t
-# Another comment""",
-                     """127.0.0.1 localhost alias # comment
-# Another comment
-""")
-
-    def test_whitespace(self):
-        self.do_test("""    \t127.0.0.1    \tlocalhost  alias # comment     \r
-    \t# Another comment""",
-                     """127.0.0.1 localhost alias # comment
-# Another comment
-""")
-
-    def test_alignment(self):
-        self.do_test("""127.0.0.1    \tlocalhost  alias
-192.168.1.1 another_host    another_alias
-""","""127.0.0.1   localhost    alias
-192.168.1.1 another_host another_alias
-""")
-
-    def test_multiple_same_name(self):
-        # The semantics are that we overwrite earlier entries with the same name
-        self.do_test("""127.0.0.1    \tlocalhost  alias
-192.168.1.1 localhost    another_alias""","""192.168.1.1 localhost another_alias
-""")
-
-if __name__ == "__main__":
-    unittest.main()
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptrunner.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptrunner.py
index 6677902a49a..d3d9d074254 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptrunner.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptrunner.py
@@ -218,6 +218,7 @@ def run_tests(config, test_paths, product, **kwargs):
                     browser_kwargs = get_browser_kwargs(test_type,
                                                         run_info,
                                                         ssl_env=ssl_env,
+                                                        config=test_environment.config,
                                                         **kwargs)
 
                     executor_cls = executor_classes.get(test_type)
diff --git a/tests/wpt/web-platform-tests/tools/wptserve/wptserve/pipes.py b/tests/wpt/web-platform-tests/tools/wptserve/wptserve/pipes.py
index b71c8afa309..534afed6b6d 100644
--- a/tests/wpt/web-platform-tests/tools/wptserve/wptserve/pipes.py
+++ b/tests/wpt/web-platform-tests/tools/wptserve/wptserve/pipes.py
@@ -392,6 +392,12 @@ def template(request, content, escape_type="html"):
             value = request.headers
         elif field == "GET":
             value = FirstWrapper(request.GET)
+        elif field == "domains":
+            if ('not_domains' in request.server.config and
+                    tokens[1][1] in request.server.config['not_domains']):
+                value = request.server.config['not_domains']
+            else:
+                value = request.server.config['domains']
         elif field in request.server.config:
             value = request.server.config[tokens[0][1]]
         elif field == "location":
diff --git a/tests/wpt/web-platform-tests/webaudio/resources/biquad-filters.js b/tests/wpt/web-platform-tests/webaudio/resources/biquad-filters.js
new file mode 100644
index 00000000000..467436326a8
--- /dev/null
+++ b/tests/wpt/web-platform-tests/webaudio/resources/biquad-filters.js
@@ -0,0 +1,376 @@
+// A biquad filter has a z-transform of
+// H(z) = (b0 + b1 / z + b2 / z^2) / (1 + a1 / z + a2 / z^2)
+//
+// The formulas for the various filters were taken from
+// http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt.
+
+
+// Lowpass filter.
+function createLowpassFilter(freq, q, gain) {
+  let b0;
+  let b1;
+  let b2;
+  let a0;
+  let a1;
+  let a2;
+
+  if (freq == 1) {
+    // The formula below works, except for roundoff.  When freq = 1,
+    // the filter is just a wire, so hardwire the coefficients.
+    b0 = 1;
+    b1 = 0;
+    b2 = 0;
+    a0 = 1;
+    a1 = 0;
+    a2 = 0;
+  } else {
+    let theta = Math.PI * freq;
+    let alpha = Math.sin(theta) / (2 * Math.pow(10, q / 20));
+    let cosw = Math.cos(theta);
+    let beta = (1 - cosw) / 2;
+
+    b0 = beta;
+    b1 = 2 * beta;
+    b2 = beta;
+    a0 = 1 + alpha;
+    a1 = -2 * cosw;
+    a2 = 1 - alpha;
+  }
+
+  return normalizeFilterCoefficients(b0, b1, b2, a0, a1, a2);
+}
+
+function createHighpassFilter(freq, q, gain) {
+  let b0;
+  let b1;
+  let b2;
+  let a0;
+  let a1;
+  let a2;
+
+  if (freq == 1) {
+    // The filter is 0
+    b0 = 0;
+    b1 = 0;
+    b2 = 0;
+    a0 = 1;
+    a1 = 0;
+    a2 = 0;
+  } else if (freq == 0) {
+    // The filter is 1.  Computation of coefficients below is ok, but
+    // there's a pole at 1 and a zero at 1, so round-off could make
+    // the filter unstable.
+    b0 = 1;
+    b1 = 0;
+    b2 = 0;
+    a0 = 1;
+    a1 = 0;
+    a2 = 0;
+  } else {
+    let theta = Math.PI * freq;
+    let alpha = Math.sin(theta) / (2 * Math.pow(10, q / 20));
+    let cosw = Math.cos(theta);
+    let beta = (1 + cosw) / 2;
+
+    b0 = beta;
+    b1 = -2 * beta;
+    b2 = beta;
+    a0 = 1 + alpha;
+    a1 = -2 * cosw;
+    a2 = 1 - alpha;
+  }
+
+  return normalizeFilterCoefficients(b0, b1, b2, a0, a1, a2);
+}
+
+function normalizeFilterCoefficients(b0, b1, b2, a0, a1, a2) {
+  let scale = 1 / a0;
+
+  return {
+    b0: b0 * scale,
+    b1: b1 * scale,
+    b2: b2 * scale,
+    a1: a1 * scale,
+    a2: a2 * scale
+  };
+}
+
+function createBandpassFilter(freq, q, gain) {
+  let b0;
+  let b1;
+  let b2;
+  let a0;
+  let a1;
+  let a2;
+  let coef;
+
+  if (freq > 0 && freq < 1) {
+    let w0 = Math.PI * freq;
+    if (q > 0) {
+      let alpha = Math.sin(w0) / (2 * q);
+      let k = Math.cos(w0);
+
+      b0 = alpha;
+      b1 = 0;
+      b2 = -alpha;
+      a0 = 1 + alpha;
+      a1 = -2 * k;
+      a2 = 1 - alpha;
+
+      coef = normalizeFilterCoefficients(b0, b1, b2, a0, a1, a2);
+    } else {
+      // q = 0, and frequency is not 0 or 1.  The above formula has a
+      // divide by zero problem.  The limit of the z-transform as q
+      // approaches 0 is 1, so set the filter that way.
+      coef = {b0: 1, b1: 0, b2: 0, a1: 0, a2: 0};
+    }
+  } else {
+    // When freq = 0 or 1, the z-transform is identically 0,
+    // independent of q.
+    coef = { b0: 0, b1: 0, b2: 0, a1: 0, a2: 0 }
+  }
+
+  return coef;
+}
+
+function createLowShelfFilter(freq, q, gain) {
+  // q not used
+  let b0;
+  let b1;
+  let b2;
+  let a0;
+  let a1;
+  let a2;
+  let coef;
+
+  let S = 1;
+  let A = Math.pow(10, gain / 40);
+
+  if (freq == 1) {
+    // The filter is just a constant gain
+    coef = {b0: A * A, b1: 0, b2: 0, a1: 0, a2: 0};
+  } else if (freq == 0) {
+    // The filter is 1
+    coef = {b0: 1, b1: 0, b2: 0, a1: 0, a2: 0};
+  } else {
+    let w0 = Math.PI * freq;
+    let alpha = 1 / 2 * Math.sin(w0) * Math.sqrt((A + 1 / A) * (1 / S - 1) + 2);
+    let k = Math.cos(w0);
+    let k2 = 2 * Math.sqrt(A) * alpha;
+    let Ap1 = A + 1;
+    let Am1 = A - 1;
+
+    b0 = A * (Ap1 - Am1 * k + k2);
+    b1 = 2 * A * (Am1 - Ap1 * k);
+    b2 = A * (Ap1 - Am1 * k - k2);
+    a0 = Ap1 + Am1 * k + k2;
+    a1 = -2 * (Am1 + Ap1 * k);
+    a2 = Ap1 + Am1 * k - k2;
+    coef = normalizeFilterCoefficients(b0, b1, b2, a0, a1, a2);
+  }
+
+  return coef;
+}
+
+function createHighShelfFilter(freq, q, gain) {
+  // q not used
+  let b0;
+  let b1;
+  let b2;
+  let a0;
+  let a1;
+  let a2;
+  let coef;
+
+  let A = Math.pow(10, gain / 40);
+
+  if (freq == 1) {
+    // When freq = 1, the z-transform is 1
+    coef = {b0: 1, b1: 0, b2: 0, a1: 0, a2: 0};
+  } else if (freq > 0) {
+    let w0 = Math.PI * freq;
+    let S = 1;
+    let alpha = 0.5 * Math.sin(w0) * Math.sqrt((A + 1 / A) * (1 / S - 1) + 2);
+    let k = Math.cos(w0);
+    let k2 = 2 * Math.sqrt(A) * alpha;
+    let Ap1 = A + 1;
+    let Am1 = A - 1;
+
+    b0 = A * (Ap1 + Am1 * k + k2);
+    b1 = -2 * A * (Am1 + Ap1 * k);
+    b2 = A * (Ap1 + Am1 * k - k2);
+    a0 = Ap1 - Am1 * k + k2;
+    a1 = 2 * (Am1 - Ap1 * k);
+    a2 = Ap1 - Am1 * k - k2;
+
+    coef = normalizeFilterCoefficients(b0, b1, b2, a0, a1, a2);
+  } else {
+    // When freq = 0, the filter is just a gain
+    coef = {b0: A * A, b1: 0, b2: 0, a1: 0, a2: 0};
+  }
+
+  return coef;
+}
+
+function createPeakingFilter(freq, q, gain) {
+  let b0;
+  let b1;
+  let b2;
+  let a0;
+  let a1;
+  let a2;
+  let coef;
+
+  let A = Math.pow(10, gain / 40);
+
+  if (freq > 0 && freq < 1) {
+    if (q > 0) {
+      let w0 = Math.PI * freq;
+      let alpha = Math.sin(w0) / (2 * q);
+      let k = Math.cos(w0);
+
+      b0 = 1 + alpha * A;
+      b1 = -2 * k;
+      b2 = 1 - alpha * A;
+      a0 = 1 + alpha / A;
+      a1 = -2 * k;
+      a2 = 1 - alpha / A;
+
+      coef = normalizeFilterCoefficients(b0, b1, b2, a0, a1, a2);
+    } else {
+      // q = 0, we have a divide by zero problem in the formulas
+      // above.  But if we look at the z-transform, we see that the
+      // limit as q approaches 0 is A^2.
+      coef = {b0: A * A, b1: 0, b2: 0, a1: 0, a2: 0};
+    }
+  } else {
+    // freq = 0 or 1, the z-transform is 1
+    coef = {b0: 1, b1: 0, b2: 0, a1: 0, a2: 0};
+  }
+
+  return coef;
+}
+
+function createNotchFilter(freq, q, gain) {
+  let b0;
+  let b1;
+  let b2;
+  let a0;
+  let a1;
+  let a2;
+  let coef;
+
+  if (freq > 0 && freq < 1) {
+    if (q > 0) {
+      let w0 = Math.PI * freq;
+      let alpha = Math.sin(w0) / (2 * q);
+      let k = Math.cos(w0);
+
+      b0 = 1;
+      b1 = -2 * k;
+      b2 = 1;
+      a0 = 1 + alpha;
+      a1 = -2 * k;
+      a2 = 1 - alpha;
+      coef = normalizeFilterCoefficients(b0, b1, b2, a0, a1, a2);
+    } else {
+      // When q = 0, we get a divide by zero above.  The limit of the
+      // z-transform as q approaches 0 is 0, so set the coefficients
+      // appropriately.
+      coef = {b0: 0, b1: 0, b2: 0, a1: 0, a2: 0};
+    }
+  } else {
+    // When freq = 0 or 1, the z-transform is 1
+    coef = {b0: 1, b1: 0, b2: 0, a1: 0, a2: 0};
+  }
+
+  return coef;
+}
+
+function createAllpassFilter(freq, q, gain) {
+  let b0;
+  let b1;
+  let b2;
+  let a0;
+  let a1;
+  let a2;
+  let coef;
+
+  if (freq > 0 && freq < 1) {
+    if (q > 0) {
+      let w0 = Math.PI * freq;
+      let alpha = Math.sin(w0) / (2 * q);
+      let k = Math.cos(w0);
+
+      b0 = 1 - alpha;
+      b1 = -2 * k;
+      b2 = 1 + alpha;
+      a0 = 1 + alpha;
+      a1 = -2 * k;
+      a2 = 1 - alpha;
+      coef = normalizeFilterCoefficients(b0, b1, b2, a0, a1, a2);
+    } else {
+      // q = 0
+      coef = {b0: -1, b1: 0, b2: 0, a1: 0, a2: 0};
+    }
+  } else {
+    coef = {b0: 1, b1: 0, b2: 0, a1: 0, a2: 0};
+  }
+
+  return coef;
+}
+
+function filterData(filterCoef, signal, len) {
+  let y = new Array(len);
+  let b0 = filterCoef.b0;
+  let b1 = filterCoef.b1;
+  let b2 = filterCoef.b2;
+  let a1 = filterCoef.a1;
+  let a2 = filterCoef.a2;
+
+  // Prime the pump. (Assumes the signal has length >= 2!)
+  y[0] = b0 * signal[0];
+  y[1] = b0 * signal[1] + b1 * signal[0] - a1 * y[0];
+
+  // Filter all of the signal that we have.
+  for (let k = 2; k < Math.min(signal.length, len); ++k) {
+    y[k] = b0 * signal[k] + b1 * signal[k - 1] + b2 * signal[k - 2] -
+        a1 * y[k - 1] - a2 * y[k - 2];
+  }
+
+  // If we need to filter more, but don't have any signal left,
+  // assume the signal is zero.
+  for (let k = signal.length; k < len; ++k) {
+    y[k] = -a1 * y[k - 1] - a2 * y[k - 2];
+  }
+
+  return y;
+}
+
+// Map the filter type name to a function that computes the filter coefficents
+// for the given filter type.
+let filterCreatorFunction = {
+  'lowpass': createLowpassFilter,
+  'highpass': createHighpassFilter,
+  'bandpass': createBandpassFilter,
+  'lowshelf': createLowShelfFilter,
+  'highshelf': createHighShelfFilter,
+  'peaking': createPeakingFilter,
+  'notch': createNotchFilter,
+  'allpass': createAllpassFilter
+};
+
+let filterTypeName = {
+  'lowpass': 'Lowpass filter',
+  'highpass': 'Highpass filter',
+  'bandpass': 'Bandpass filter',
+  'lowshelf': 'Lowshelf filter',
+  'highshelf': 'Highshelf filter',
+  'peaking': 'Peaking filter',
+  'notch': 'Notch filter',
+  'allpass': 'Allpass filter'
+};
+
+function createFilter(filterType, freq, q, gain) {
+  return filterCreatorFunction[filterType](freq, q, gain);
+}
diff --git a/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-iirfilternode-interface/iirfilter-basic.html b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-iirfilternode-interface/iirfilter-basic.html
new file mode 100644
index 00000000000..da36d583dd5
--- /dev/null
+++ b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-iirfilternode-interface/iirfilter-basic.html
@@ -0,0 +1,204 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>
+      Test Basic IIRFilterNode Properties
+    </title>
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+    <script src="../../resources/audit-util.js"></script>
+    <script src="../../resources/audit.js"></script>
+  </head>
+  <body>
+    <script id="layout-test-code">
+      let sampleRate = 48000;
+      let testFrames = 100;
+
+      // Global context that can be used by the individual tasks. It must be
+      // defined by the initialize task.
+      let context;
+
+      let audit = Audit.createTaskRunner();
+
+      audit.define('initialize', (task, should) => {
+        should(() => {
+          context = new OfflineAudioContext(1, testFrames, sampleRate);
+        }, 'Initialize context for testing').notThrow();
+        task.done();
+      });
+
+      audit.define('existence', (task, should) => {
+        should(context.createIIRFilter, 'context.createIIRFilter').exist();
+        task.done();
+      });
+
+      audit.define('parameters', (task, should) => {
+        // Create a really simple IIR filter. Doesn't much matter what.
+        let coef = Float32Array.from([1]);
+
+        let f = context.createIIRFilter(coef, coef);
+
+        should(f.numberOfInputs, 'numberOfInputs').beEqualTo(1);
+        should(f.numberOfOutputs, 'numberOfOutputs').beEqualTo(1);
+        should(f.channelCountMode, 'channelCountMode').beEqualTo('max');
+        should(f.channelInterpretation, 'channelInterpretation')
+            .beEqualTo('speakers');
+
+        task.done();
+      });
+
+      audit.define('exceptions-createIIRFilter', (task, should) => {
+        should(function() {
+          // Two args are required.
+          context.createIIRFilter();
+        }, 'createIIRFilter()').throw('TypeError');
+
+        should(function() {
+          // Two args are required.
+          context.createIIRFilter(new Float32Array(1));
+        }, 'createIIRFilter(new Float32Array(1))').throw('TypeError');
+
+        should(function() {
+          // null is not valid
+          context.createIIRFilter(null, null);
+        }, 'createIIRFilter(null, null)').throw('TypeError');
+
+        should(function() {
+          // There has to be at least one coefficient.
+          context.createIIRFilter([], []);
+        }, 'createIIRFilter([], [])').throw('NotSupportedError');
+
+        should(function() {
+          // There has to be at least one coefficient.
+          context.createIIRFilter([1], []);
+        }, 'createIIRFilter([1], [])').throw('NotSupportedError');
+
+        should(function() {
+          // There has to be at least one coefficient.
+          context.createIIRFilter([], [1]);
+        }, 'createIIRFilter([], [1])').throw('NotSupportedError');
+
+        should(
+            function() {
+              // Max allowed size for the coefficient arrays.
+              let fb = new Float32Array(20);
+              fb[0] = 1;
+              context.createIIRFilter(fb, fb);
+            },
+            'createIIRFilter(new Float32Array(20), new Float32Array(20))')
+            .notThrow();
+
+        should(
+            function() {
+              // Max allowed size for the feedforward coefficient array.
+              let coef = new Float32Array(21);
+              coef[0] = 1;
+              context.createIIRFilter(coef, [1]);
+            },
+            'createIIRFilter(new Float32Array(21), [1])')
+            .throw('NotSupportedError');
+
+        should(
+            function() {
+              // Max allowed size for the feedback coefficient array.
+              let coef = new Float32Array(21);
+              coef[0] = 1;
+              context.createIIRFilter([1], coef);
+            },
+            'createIIRFilter([1], new Float32Array(21))')
+            .throw('NotSupportedError');
+
+        should(
+            function() {
+              // First feedback coefficient can't be 0.
+              context.createIIRFilter([1], new Float32Array(2));
+            },
+            'createIIRFilter([1], new Float32Array(2))')
+            .throw('InvalidStateError');
+
+        should(
+            function() {
+              // feedforward coefficients can't all be zero.
+              context.createIIRFilter(new Float32Array(10), [1]);
+            },
+            'createIIRFilter(new Float32Array(10), [1])')
+            .throw('InvalidStateError');
+
+        should(function() {
+          // Feedback coefficients must be finite.
+          context.createIIRFilter([1], [1, Infinity, NaN]);
+        }, 'createIIRFilter([1], [1, NaN, Infinity])').throw('TypeError');
+
+        should(function() {
+          // Feedforward coefficients must be finite.
+          context.createIIRFilter([1, Infinity, NaN], [1]);
+        }, 'createIIRFilter([1, NaN, Infinity], [1])').throw('TypeError');
+
+        should(function() {
+          // Test that random junk in the array is converted to NaN.
+          context.createIIRFilter([1, 'abc', []], [1]);
+        }, 'createIIRFilter([1, \'abc\', []], [1])').throw('TypeError');
+
+        task.done();
+      });
+
+      audit.define('exceptions-getFrequencyData', (task, should) => {
+        // Create a really simple IIR filter. Doesn't much matter what.
+        let coef = Float32Array.from([1]);
+
+        let f = context.createIIRFilter(coef, coef);
+
+        should(
+            function() {
+              // frequencyHz can't be null.
+              f.getFrequencyResponse(
+                  null, new Float32Array(1), new Float32Array(1));
+            },
+            'getFrequencyResponse(null, new Float32Array(1), new Float32Array(1))')
+            .throw('TypeError');
+
+        should(
+            function() {
+              // magResponse can't be null.
+              f.getFrequencyResponse(
+                  new Float32Array(1), null, new Float32Array(1));
+            },
+            'getFrequencyResponse(new Float32Array(1), null, new Float32Array(1))')
+            .throw('TypeError');
+
+        should(
+            function() {
+              // phaseResponse can't be null.
+              f.getFrequencyResponse(
+                  new Float32Array(1), new Float32Array(1), null);
+            },
+            'getFrequencyResponse(new Float32Array(1), new Float32Array(1), null)')
+            .throw('TypeError');
+
+        should(
+            function() {
+              // magResponse array must the same length as frequencyHz
+              f.getFrequencyResponse(
+                  new Float32Array(10), new Float32Array(1),
+                  new Float32Array(20));
+            },
+            'getFrequencyResponse(new Float32Array(10), new Float32Array(1), new Float32Array(20))')
+            .throw('InvalidAccessError');
+
+        should(
+            function() {
+              // phaseResponse array must be the same length as frequencyHz
+              f.getFrequencyResponse(
+                  new Float32Array(10), new Float32Array(20),
+                  new Float32Array(1));
+            },
+            'getFrequencyResponse(new Float32Array(10), new Float32Array(20), new Float32Array(1))')
+            .throw('InvalidAccessError');
+
+        task.done();
+      });
+
+      audit.run();
+    </script>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-iirfilternode-interface/iirfilter-getFrequencyResponse.html b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-iirfilternode-interface/iirfilter-getFrequencyResponse.html
new file mode 100644
index 00000000000..c98555f1610
--- /dev/null
+++ b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-iirfilternode-interface/iirfilter-getFrequencyResponse.html
@@ -0,0 +1,159 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>
+      Test IIRFilter getFrequencyResponse() functionality
+    </title>
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+    <script src="../../resources/audit-util.js"></script>
+    <script src="../../resources/audit.js"></script>
+    <script src="../../resources/biquad-filters.js"></script>
+  </head>
+  <body>
+    <script id="layout-test-code">
+      let sampleRate = 48000;
+      // Some short duration; we're not actually looking at the rendered output.
+      let testDurationSec = 0.01;
+
+      // Number of frequency samples to take.
+      let numberOfFrequencies = 1000;
+
+      let audit = Audit.createTaskRunner();
+
+
+      // Compute a set of linearly spaced frequencies.
+      function createFrequencies(nFrequencies, sampleRate) {
+        let frequencies = new Float32Array(nFrequencies);
+        let nyquist = sampleRate / 2;
+        let freqDelta = nyquist / nFrequencies;
+
+        for (let k = 0; k < nFrequencies; ++k) {
+          frequencies[k] = k * freqDelta;
+        }
+
+        return frequencies;
+      }
+
+      audit.define('1-pole IIR', (task, should) => {
+        let context = new OfflineAudioContext(
+            1, testDurationSec * sampleRate, sampleRate);
+
+        let iir = context.createIIRFilter([1], [1, -0.9]);
+        let frequencies =
+            createFrequencies(numberOfFrequencies, context.sampleRate);
+
+        let iirMag = new Float32Array(numberOfFrequencies);
+        let iirPhase = new Float32Array(numberOfFrequencies);
+        let trueMag = new Float32Array(numberOfFrequencies);
+        let truePhase = new Float32Array(numberOfFrequencies);
+
+        // The IIR filter is
+        //   H(z) = 1/(1 - 0.9*z^(-1)).
+        //
+        // The frequency response is
+        //   H(exp(j*w)) = 1/(1 - 0.9*exp(-j*w)).
+        //
+        // Thus, the magnitude is
+        //   |H(exp(j*w))| = 1/sqrt(1.81-1.8*cos(w)).
+        //
+        // The phase is
+        //   arg(H(exp(j*w)) = atan(0.9*sin(w)/(.9*cos(w)-1))
+
+        let frequencyScale = Math.PI / (sampleRate / 2);
+
+        for (let k = 0; k < frequencies.length; ++k) {
+          let omega = frequencyScale * frequencies[k];
+          trueMag[k] = 1 / Math.sqrt(1.81 - 1.8 * Math.cos(omega));
+          truePhase[k] =
+              Math.atan(0.9 * Math.sin(omega) / (0.9 * Math.cos(omega) - 1));
+        }
+
+        iir.getFrequencyResponse(frequencies, iirMag, iirPhase);
+
+        // Thresholds were experimentally determined.
+        should(iirMag, '1-pole IIR Magnitude Response')
+            .beCloseToArray(trueMag, {absoluteThreshold: 2.8611e-6});
+        should(iirPhase, '1-pole IIR Phase Response')
+            .beCloseToArray(truePhase, {absoluteThreshold: 1.7882e-7});
+
+        task.done();
+      });
+
+      audit.define('compare IIR and biquad', (task, should) => {
+        // Create an IIR filter equivalent to the biquad filter. Compute the
+        // frequency response for both and verify that they are the same.
+        let context = new OfflineAudioContext(
+            1, testDurationSec * sampleRate, sampleRate);
+
+        let biquad = context.createBiquadFilter();
+        let coef = createFilter(
+            biquad.type, biquad.frequency.value / (context.sampleRate / 2),
+            biquad.Q.value, biquad.gain.value);
+
+        let iir = context.createIIRFilter(
+            [coef.b0, coef.b1, coef.b2], [1, coef.a1, coef.a2]);
+
+        let frequencies =
+            createFrequencies(numberOfFrequencies, context.sampleRate);
+        let biquadMag = new Float32Array(numberOfFrequencies);
+        let biquadPhase = new Float32Array(numberOfFrequencies);
+        let iirMag = new Float32Array(numberOfFrequencies);
+        let iirPhase = new Float32Array(numberOfFrequencies);
+
+        biquad.getFrequencyResponse(frequencies, biquadMag, biquadPhase);
+        iir.getFrequencyResponse(frequencies, iirMag, iirPhase);
+
+        // Thresholds were experimentally determined.
+        should(iirMag, 'IIR Magnitude Response').beCloseToArray(biquadMag, {
+          absoluteThreshold: 2.7419e-5
+        });
+        should(iirPhase, 'IIR Phase Response').beCloseToArray(biquadPhase, {
+          absoluteThreshold: 2.7657e-5
+        });
+
+        task.done();
+      });
+
+      audit.define(
+          {
+            label: 'getFrequencyResponse',
+            description: 'Test out-of-bounds frequency values'
+          },
+          (task, should) => {
+            let context = new OfflineAudioContext(1, 1, sampleRate);
+            let filter = new IIRFilterNode(
+                context, {feedforward: [1], feedback: [1, -.9]});
+
+            // Frequencies to test.  These are all outside the valid range of
+            // frequencies of 0 to Nyquist.
+            let freq = new Float32Array(2);
+            freq[0] = -1;
+            freq[1] = context.sampleRate / 2 + 1;
+
+            let mag = new Float32Array(freq.length);
+            let phase = new Float32Array(freq.length);
+
+            filter.getFrequencyResponse(freq, mag, phase);
+
+            // Verify that the returned magnitude and phase entries are alL NaN
+            // since the frequencies are outside the valid range
+            for (let k = 0; k < mag.length; ++k) {
+              should(mag[k],
+                  'Magnitude response at frequency ' + freq[k])
+                  .beNaN();
+            }
+
+            for (let k = 0; k < phase.length; ++k) {
+              should(phase[k],
+                  'Phase response at frequency ' + freq[k])
+                  .beNaN();
+            }
+
+            task.done();
+          });
+
+      audit.run();
+    </script>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-iirfilternode-interface/iirfilter.html b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-iirfilternode-interface/iirfilter.html
new file mode 100644
index 00000000000..aa38a6bfcad
--- /dev/null
+++ b/tests/wpt/web-platform-tests/webaudio/the-audio-api/the-iirfilternode-interface/iirfilter.html
@@ -0,0 +1,572 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>
+      Test Basic IIRFilterNode Operation
+    </title>
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+    <script src="../../resources/audit-util.js"></script>
+    <script src="../../resources/audit.js"></script>
+    <script src="../../resources/biquad-filters.js"></script>
+  </head>
+  <body>
+    <script id="layout-test-code">
+      let sampleRate = 24000;
+      let testDurationSec = 0.25;
+      let testFrames = testDurationSec * sampleRate;
+
+      let audit = Audit.createTaskRunner();
+
+      audit.define('coefficient-normalization', (task, should) => {
+        // Test that the feedback coefficients are normalized.  Do this be
+        // creating two IIRFilterNodes.  One has normalized coefficients, and
+        // one doesn't.  Compute the difference and make sure they're the same.
+        let context = new OfflineAudioContext(2, testFrames, sampleRate);
+
+        // Use a simple impulse as the source.
+        let buffer = context.createBuffer(1, 1, sampleRate);
+        buffer.getChannelData(0)[0] = 1;
+        let source = context.createBufferSource();
+        source.buffer = buffer;
+
+        // Gain node for computing the difference between the filters.
+        let gain = context.createGain();
+        gain.gain.value = -1;
+
+        // The IIR filters.  Use a common feedforward array.
+        let ff = [1];
+
+        let fb1 = [1, .9];
+
+        let fb2 = new Float64Array(2);
+        // Scale the feedback coefficients by an arbitrary factor.
+        let coefScaleFactor = 2;
+        for (let k = 0; k < fb2.length; ++k) {
+          fb2[k] = coefScaleFactor * fb1[k];
+        }
+
+        let iir1;
+        let iir2;
+
+        should(function() {
+          iir1 = context.createIIRFilter(ff, fb1);
+        }, 'createIIRFilter with normalized coefficients').notThrow();
+
+        should(function() {
+          iir2 = context.createIIRFilter(ff, fb2);
+        }, 'createIIRFilter with unnormalized coefficients').notThrow();
+
+        // Create the graph.  The output of iir1 (normalized coefficients) is
+        // channel 0, and the output of iir2 (unnormalized coefficients), with
+        // appropriate scaling, is channel 1.
+        let merger = context.createChannelMerger(2);
+        source.connect(iir1);
+        source.connect(iir2);
+        iir1.connect(merger, 0, 0);
+        iir2.connect(gain);
+
+        // The gain for the gain node should be set to compensate for the
+        // scaling of the coefficients.  Since iir2 has scaled the coefficients
+        // by coefScaleFactor, the output is reduced by the same factor, so
+        // adjust the gain to scale the output of iir2 back up.
+        gain.gain.value = coefScaleFactor;
+        gain.connect(merger, 0, 1);
+
+        merger.connect(context.destination);
+
+        source.start();
+
+        // Rock and roll!
+
+        context.startRendering()
+            .then(function(result) {
+              // Find the max amplitude of the result, which should be near
+              // zero.
+              let iir1Data = result.getChannelData(0);
+              let iir2Data = result.getChannelData(1);
+
+              // Threshold isn't exactly zero because the arithmetic is done
+              // differently between the IIRFilterNode and the BiquadFilterNode.
+              should(
+                  iir2Data,
+                  'Output of IIR filter with unnormalized coefficients')
+                  .beCloseToArray(iir1Data, {absoluteThreshold: 2.1958e-38});
+            })
+            .then(() => task.done());
+      });
+
+      audit.define('one-zero', (task, should) => {
+        // Create a simple 1-zero filter and compare with the expected output.
+        let context = new OfflineAudioContext(1, testFrames, sampleRate);
+
+        // Use a simple impulse as the source
+        let buffer = context.createBuffer(1, 1, sampleRate);
+        buffer.getChannelData(0)[0] = 1;
+        let source = context.createBufferSource();
+        source.buffer = buffer;
+
+        // The filter is y(n) = 0.5*(x(n) + x(n-1)), a simple 2-point moving
+        // average.  This is rather arbitrary; keep it simple.
+
+        let iir = context.createIIRFilter([0.5, 0.5], [1]);
+
+        // Create the graph
+        source.connect(iir);
+        iir.connect(context.destination);
+
+        // Rock and roll!
+        source.start();
+
+        context.startRendering()
+            .then(function(result) {
+              let actual = result.getChannelData(0);
+              let expected = new Float64Array(testFrames);
+              // The filter is a simple 2-point moving average of an impulse, so
+              // the first two values are non-zero and the rest are zero.
+              expected[0] = 0.5;
+              expected[1] = 0.5;
+              should(actual, 'IIR 1-zero output').beCloseToArray(expected, {
+                absoluteThreshold: 0
+              });
+            })
+            .then(() => task.done());
+      });
+
+      audit.define('one-pole', (task, should) => {
+        // Create a simple 1-pole filter and compare with the expected output.
+
+        // The filter is y(n) + c*y(n-1)= x(n).  The analytical response is
+        // (-c)^n, so choose a suitable number of frames to run the test for
+        // where the output isn't flushed to zero.
+        let c = 0.9;
+        let eps = 1e-20;
+        let duration = Math.floor(Math.log(eps) / Math.log(Math.abs(c)));
+        let context = new OfflineAudioContext(1, duration, sampleRate);
+
+        // Use a simple impulse as the source
+        let buffer = context.createBuffer(1, 1, sampleRate);
+        buffer.getChannelData(0)[0] = 1;
+        let source = context.createBufferSource();
+        source.buffer = buffer;
+
+        let iir = context.createIIRFilter([1], [1, c]);
+
+        // Create the graph
+        source.connect(iir);
+        iir.connect(context.destination);
+
+        // Rock and roll!
+        source.start();
+
+        context.startRendering()
+            .then(function(result) {
+              let actual = result.getChannelData(0);
+              let expected = new Float64Array(actual.length);
+
+              // The filter is a simple 1-pole filter: y(n) = -c*y(n-k)+x(n),
+              // with an impulse as the input.
+              expected[0] = 1;
+              for (k = 1; k < testFrames; ++k) {
+                expected[k] = -c * expected[k - 1];
+              }
+
+              // Threshold isn't exactly zero due to round-off in the
+              // single-precision IIRFilterNode computations versus the
+              // double-precision Javascript computations.
+              should(actual, 'IIR 1-pole output').beCloseToArray(expected, {
+                absoluteThreshold: 2.7657e-8
+              });
+            })
+            .then(() => task.done());
+      });
+
+      // Return a function suitable for use as a defineTask function.  This
+      // function creates an IIRFilterNode equivalent to the specified
+      // BiquadFilterNode and compares the outputs.  The outputs from the two
+      // filters should be virtually identical.
+      function testWithBiquadFilter(filterType, errorThreshold, snrThreshold) {
+        return (task, should) => {
+          let context = new OfflineAudioContext(2, testFrames, sampleRate);
+
+          // Use a constant (step function) as the source
+          let buffer = createConstantBuffer(context, testFrames, 1);
+          let source = context.createBufferSource();
+          source.buffer = buffer;
+
+
+          // Create the biquad.  Choose some rather arbitrary values for Q and
+          // gain for the biquad so that the shelf filters aren't identical.
+          let biquad = context.createBiquadFilter();
+          biquad.type = filterType;
+          biquad.Q.value = 10;
+          biquad.gain.value = 10;
+
+          // Create the equivalent IIR Filter node by computing the coefficients
+          // of the given biquad filter type.
+          let nyquist = sampleRate / 2;
+          let coef = createFilter(
+              filterType, biquad.frequency.value / nyquist, biquad.Q.value,
+              biquad.gain.value);
+
+          let iir = context.createIIRFilter(
+              [coef.b0, coef.b1, coef.b2], [1, coef.a1, coef.a2]);
+
+          let merger = context.createChannelMerger(2);
+          // Create the graph
+          source.connect(biquad);
+          source.connect(iir);
+
+          biquad.connect(merger, 0, 0);
+          iir.connect(merger, 0, 1);
+
+          merger.connect(context.destination);
+
+          // Rock and roll!
+          source.start();
+
+          context.startRendering()
+              .then(function(result) {
+                // Find the max amplitude of the result, which should be near
+                // zero.
+                let expected = result.getChannelData(0);
+                let actual = result.getChannelData(1);
+
+                // On MacOSX, WebAudio uses an optimized Biquad implementation
+                // that is different from the implementation used for Linux and
+                // Windows.  This will cause the output to differ, even if the
+                // threshold passes.  Thus, only print out a very small number
+                // of elements of the array where we have tested that they are
+                // consistent.
+                should(actual, 'IIRFilter for Biquad ' + filterType)
+                    .beCloseToArray(expected, errorThreshold);
+
+                let snr = 10 * Math.log10(computeSNR(actual, expected));
+                should(snr, 'SNR for IIRFIlter for Biquad ' + filterType)
+                    .beGreaterThanOrEqualTo(snrThreshold);
+              })
+              .then(() => task.done());
+        };
+      }
+
+      // Thresholds here are experimentally determined.
+      let biquadTestConfigs = [
+        {
+          filterType: 'lowpass',
+          snrThreshold: 91.221,
+          errorThreshold: {relativeThreshold: 4.9834e-5}
+        },
+        {
+          filterType: 'highpass',
+          snrThreshold: 105.4590,
+          errorThreshold: {absoluteThreshold: 2.9e-6, relativeThreshold: 3e-5}
+        },
+        {
+          filterType: 'bandpass',
+          snrThreshold: 104.060,
+          errorThreshold: {absoluteThreshold: 2e-7, relativeThreshold: 8.7e-4}
+        },
+        {
+          filterType: 'notch',
+          snrThreshold: 91.312,
+          errorThreshold: {absoluteThreshold: 0, relativeThreshold: 4.22e-5}
+        },
+        {
+          filterType: 'allpass',
+          snrThreshold: 91.319,
+          errorThreshold: {absoluteThreshold: 0, relativeThreshold: 4.31e-5}
+        },
+        {
+          filterType: 'lowshelf',
+          snrThreshold: 90.609,
+          errorThreshold: {absoluteThreshold: 0, relativeThreshold: 2.98e-5}
+        },
+        {
+          filterType: 'highshelf',
+          snrThreshold: 103.159,
+          errorThreshold: {absoluteThreshold: 0, relativeThreshold: 1.24e-5}
+        },
+        {
+          filterType: 'peaking',
+          snrThreshold: 91.504,
+          errorThreshold: {absoluteThreshold: 0, relativeThreshold: 5.05e-5}
+        }
+      ];
+
+      // Create a set of tasks based on biquadTestConfigs.
+      for (k = 0; k < biquadTestConfigs.length; ++k) {
+        let config = biquadTestConfigs[k];
+        let name = k + ': ' + config.filterType;
+        audit.define(
+            name,
+            testWithBiquadFilter(
+                config.filterType, config.errorThreshold, config.snrThreshold));
+      }
+
+      audit.define('multi-channel', (task, should) => {
+        // Multi-channel test.  Create a biquad filter and the equivalent IIR
+        // filter.  Filter the same multichannel signal and compare the results.
+        let nChannels = 3;
+        let context =
+            new OfflineAudioContext(nChannels, testFrames, sampleRate);
+
+        // Create a set of oscillators as the multi-channel source.
+        let source = [];
+
+        for (k = 0; k < nChannels; ++k) {
+          source[k] = context.createOscillator();
+          source[k].type = 'sawtooth';
+          // The frequency of the oscillator is pretty arbitrary, but each
+          // oscillator should have a different frequency.
+          source[k].frequency.value = 100 + k * 100;
+        }
+
+        let merger = context.createChannelMerger(3);
+
+        let biquad = context.createBiquadFilter();
+
+        // Create the equivalent IIR Filter node.
+        let nyquist = sampleRate / 2;
+        let coef = createFilter(
+            biquad.type, biquad.frequency.value / nyquist, biquad.Q.value,
+            biquad.gain.value);
+        let fb = [1, coef.a1, coef.a2];
+        let ff = [coef.b0, coef.b1, coef.b2];
+
+        let iir = context.createIIRFilter(ff, fb);
+        // Gain node to compute the difference between the IIR and biquad
+        // filter.
+        let gain = context.createGain();
+        gain.gain.value = -1;
+
+        // Create the graph.
+        for (k = 0; k < nChannels; ++k)
+          source[k].connect(merger, 0, k);
+
+        merger.connect(biquad);
+        merger.connect(iir);
+        iir.connect(gain);
+        biquad.connect(context.destination);
+        gain.connect(context.destination);
+
+        for (k = 0; k < nChannels; ++k)
+          source[k].start();
+
+        context.startRendering()
+            .then(function(result) {
+              let errorThresholds = [3.7671e-5, 3.0071e-5, 2.6241e-5];
+
+              // Check the difference signal on each channel
+              for (channel = 0; channel < result.numberOfChannels; ++channel) {
+                // Find the max amplitude of the result, which should be near
+                // zero.
+                let data = result.getChannelData(channel);
+                let maxError =
+                    data.reduce(function(reducedValue, currentValue) {
+                      return Math.max(reducedValue, Math.abs(currentValue));
+                    });
+
+                should(
+                    maxError,
+                    'Max difference between IIR and Biquad on channel ' +
+                        channel)
+                    .beLessThanOrEqualTo(errorThresholds[channel]);
+              }
+
+            })
+            .then(() => task.done());
+      });
+
+      // Apply an IIRFilter to the given input signal.
+      //
+      // IIR filter in the time domain is
+      //
+      //   y[n] = sum(ff[k]*x[n-k], k, 0, M) - sum(fb[k]*y[n-k], k, 1, N)
+      //
+      function iirFilter(input, feedforward, feedback) {
+        // For simplicity, create an x buffer that contains the input, and a y
+        // buffer that contains the output.  Both of these buffers have an
+        // initial work space to implement the initial memory of the filter.
+        let workSize = Math.max(feedforward.length, feedback.length);
+        let x = new Float32Array(input.length + workSize);
+
+        // Float64 because we want to match the implementation that uses doubles
+        // to minimize roundoff.
+        let y = new Float64Array(input.length + workSize);
+
+        // Copy the input over.
+        for (let k = 0; k < input.length; ++k)
+          x[k + feedforward.length] = input[k];
+
+        // Run the filter
+        for (let n = 0; n < input.length; ++n) {
+          let index = n + workSize;
+          let yn = 0;
+          for (let k = 0; k < feedforward.length; ++k)
+            yn += feedforward[k] * x[index - k];
+          for (let k = 0; k < feedback.length; ++k)
+            yn -= feedback[k] * y[index - k];
+
+          y[index] = yn;
+        }
+
+        return y.slice(workSize).map(Math.fround);
+      }
+
+      // Cascade the two given biquad filters to create one IIR filter.
+      function cascadeBiquads(f1Coef, f2Coef) {
+        // The biquad filters are:
+        //
+        // f1 = (b10 + b11/z + b12/z^2)/(1 + a11/z + a12/z^2);
+        // f2 = (b20 + b21/z + b22/z^2)/(1 + a21/z + a22/z^2);
+        //
+        // To cascade them, multiply the two transforms together to get a fourth
+        // order IIR filter.
+
+        let numProduct = [
+          f1Coef.b0 * f2Coef.b0, f1Coef.b0 * f2Coef.b1 + f1Coef.b1 * f2Coef.b0,
+          f1Coef.b0 * f2Coef.b2 + f1Coef.b1 * f2Coef.b1 + f1Coef.b2 * f2Coef.b0,
+          f1Coef.b1 * f2Coef.b2 + f1Coef.b2 * f2Coef.b1, f1Coef.b2 * f2Coef.b2
+        ];
+
+        let denProduct = [
+          1, f2Coef.a1 + f1Coef.a1,
+          f2Coef.a2 + f1Coef.a1 * f2Coef.a1 + f1Coef.a2,
+          f1Coef.a1 * f2Coef.a2 + f1Coef.a2 * f2Coef.a1, f1Coef.a2 * f2Coef.a2
+        ];
+
+        return {
+          ff: numProduct, fb: denProduct
+        }
+      }
+
+      // Find the magnitude of the root of the quadratic that has the maximum
+      // magnitude.
+      //
+      // The quadratic is z^2 + a1 * z + a2 and we want the root z that has the
+      // largest magnitude.
+      function largestRootMagnitude(a1, a2) {
+        let discriminant = a1 * a1 - 4 * a2;
+        if (discriminant < 0) {
+          // Complex roots:  -a1/2 +/- i*sqrt(-d)/2.  Thus the magnitude of each
+          // root is the same and is sqrt(a1^2/4 + |d|/4)
+          let d = Math.sqrt(-discriminant);
+          return Math.hypot(a1 / 2, d / 2);
+        } else {
+          // Real roots
+          let d = Math.sqrt(discriminant);
+          return Math.max(Math.abs((-a1 + d) / 2), Math.abs((-a1 - d) / 2));
+        }
+      }
+
+      audit.define('4th-order-iir', (task, should) => {
+        // Cascade 2 lowpass biquad filters and compare that with the equivalent
+        // 4th order IIR filter.
+
+        let nyquist = sampleRate / 2;
+        // Compute the coefficients of a lowpass filter.
+
+        // First some preliminary stuff.  Compute the coefficients of the
+        // biquad.  This is used to figure out how frames to use in the test.
+        let biquadType = 'lowpass';
+        let biquadCutoff = 350;
+        let biquadQ = 5;
+        let biquadGain = 1;
+
+        let coef = createFilter(
+            biquadType, biquadCutoff / nyquist, biquadQ, biquadGain);
+
+        // Cascade the biquads together to create an equivalent IIR filter.
+        let cascade = cascadeBiquads(coef, coef);
+
+        // Since we're cascading two identical biquads, the root of denominator
+        // of the IIR filter is repeated, so the root of the denominator with
+        // the largest magnitude occurs twice.  The impulse response of the IIR
+        // filter will be roughly c*(r*r)^n at time n, where r is the root of
+        // largest magnitude.  This approximation gets better as n increases.
+        // We can use this to get a rough idea of when the response has died
+        // down to a small value.
+
+        // This is the value we will use to determine how many frames to render.
+        // Rendering too many is a waste of time and also makes it hard to
+        // compare the actual result to the expected because the magnitudes are
+        // so small that they could be mostly round-off noise.
+        //
+        // Find magnitude of the root with largest magnitude
+        let rootMagnitude = largestRootMagnitude(coef.a1, coef.a2);
+
+        // Find n such that |r|^(2*n) <= eps.  That is, n = log(eps)/(2*log(r)).
+        // Somewhat arbitrarily choose eps = 1e-20;
+        let eps = 1e-20;
+        let framesForTest =
+            Math.floor(Math.log(eps) / (2 * Math.log(rootMagnitude)));
+
+        // We're ready to create the graph for the test.  The offline context
+        // has two channels: channel 0 is the expected (cascaded biquad) result
+        // and channel 1 is the actual IIR filter result.
+        let context = new OfflineAudioContext(2, framesForTest, sampleRate);
+
+        // Use a simple impulse with a large (arbitrary) amplitude as the source
+        let amplitude = 1;
+        let buffer = context.createBuffer(1, testFrames, sampleRate);
+        buffer.getChannelData(0)[0] = amplitude;
+        let source = context.createBufferSource();
+        source.buffer = buffer;
+
+        // Create the two biquad filters.  Doesn't really matter what, but for
+        // simplicity we choose identical lowpass filters with the same
+        // parameters.
+        let biquad1 = context.createBiquadFilter();
+        biquad1.type = biquadType;
+        biquad1.frequency.value = biquadCutoff;
+        biquad1.Q.value = biquadQ;
+
+        let biquad2 = context.createBiquadFilter();
+        biquad2.type = biquadType;
+        biquad2.frequency.value = biquadCutoff;
+        biquad2.Q.value = biquadQ;
+
+        let iir = context.createIIRFilter(cascade.ff, cascade.fb);
+
+        // Create the merger to get the signals into multiple channels
+        let merger = context.createChannelMerger(2);
+
+        // Create the graph, filtering the source through two biquads.
+        source.connect(biquad1);
+        biquad1.connect(biquad2);
+        biquad2.connect(merger, 0, 0);
+
+        source.connect(iir);
+        iir.connect(merger, 0, 1);
+
+        merger.connect(context.destination);
+
+        // Now filter the source through the IIR filter.
+        let y = iirFilter(buffer.getChannelData(0), cascade.ff, cascade.fb);
+
+        // Rock and roll!
+        source.start();
+
+        context.startRendering()
+            .then(function(result) {
+              let expected = result.getChannelData(0);
+              let actual = result.getChannelData(1);
+
+              should(actual, '4-th order IIRFilter (biquad ref)')
+                  .beCloseToArray(expected, {
+                    // Thresholds experimentally determined.
+                    absoluteThreshold: 1.59e-7,
+                    relativeThreshold: 2.11e-5,
+                  });
+
+              let snr = 10 * Math.log10(computeSNR(actual, expected));
+              should(snr, 'SNR of 4-th order IIRFilter (biquad ref)')
+                  .beGreaterThanOrEqualTo(108.947);
+            })
+            .then(() => task.done());
+      });
+
+      audit.run();
+    </script>
+  </body>
+</html>
diff --git a/tests/wpt/web-platform-tests/webdriver/tests/actions/mouse.py b/tests/wpt/web-platform-tests/webdriver/tests/actions/mouse.py
index bb7e1451aae..f8526539b81 100644
--- a/tests/wpt/web-platform-tests/webdriver/tests/actions/mouse.py
+++ b/tests/wpt/web-platform-tests/webdriver/tests/actions/mouse.py
@@ -1,6 +1,6 @@
 import pytest
 
-from tests.actions.support.mouse import get_center
+from tests.actions.support.mouse import get_inview_center, get_viewport_rect
 from tests.actions.support.refine import get_events, filter_dict
 from tests.support.asserts import assert_move_to_coordinates
 from tests.support.inline import inline
@@ -12,11 +12,6 @@ def link_doc(dest):
     return inline(content)
 
 
-# TODO use pytest.approx once we upgrade to pytest > 3.0
-def approx(n, m, tolerance=1):
-    return abs(n - m) <= tolerance
-
-
 def test_click_at_coordinates(session, test_actions_page, mouse_chain):
     div_point = {
         "x": 82,
@@ -35,7 +30,7 @@ def test_click_at_coordinates(session, test_actions_page, mouse_chain):
         assert e["button"] == 0
     expected = [
         {"type": "mousedown", "buttons": 1},
-        {"type": "mouseup",  "buttons": 0},
+        {"type": "mouseup", "buttons": 0},
         {"type": "click", "buttons": 0},
     ]
     filtered_events = [filter_dict(e, expected[0]) for e in events]
@@ -55,7 +50,7 @@ def test_context_menu_at_coordinates(session, test_actions_page, mouse_chain):
     events = get_events(session)
     expected = [
         {"type": "mousedown", "button": 2},
-        {"type": "contextmenu",  "button": 2},
+        {"type": "contextmenu", "button": 2},
     ]
     assert len(events) == 4
     filtered_events = [filter_dict(e, expected[0]) for e in events]
@@ -68,7 +63,7 @@ def test_context_menu_at_coordinates(session, test_actions_page, mouse_chain):
 
 def test_click_element_center(session, test_actions_page, mouse_chain):
     outer = session.find.css("#outer", all=False)
-    center = get_center(outer.rect)
+    center = get_inview_center(outer.rect, get_viewport_rect(session))
     mouse_chain.click(element=outer).perform()
     events = get_events(session)
     assert len(events) == 4
@@ -76,8 +71,8 @@ def test_click_element_center(session, test_actions_page, mouse_chain):
     assert ["mousemove", "mousedown", "mouseup", "click"] == event_types
     for e in events:
         if e["type"] != "mousemove":
-            assert approx(e["pageX"], center["x"])
-            assert approx(e["pageY"], center["y"])
+            assert pytest.approx(e["pageX"], center["x"])
+            assert pytest.approx(e["pageY"], center["y"])
             assert e["target"] == "outer"
 
 
@@ -102,8 +97,9 @@ def test_click_navigation(session, url, release_actions):
 
 
 @pytest.mark.parametrize("drag_duration", [0, 300, 800])
-@pytest.mark.parametrize("dx, dy",
-    [(20, 0), (0, 15), (10, 15), (-20, 0), (10, -15), (-10, -15)])
+@pytest.mark.parametrize("dx, dy", [
+    (20, 0), (0, 15), (10, 15), (-20, 0), (10, -15), (-10, -15)
+])
 def test_drag_and_drop(session,
                        test_actions_page,
                        mouse_chain,
@@ -112,7 +108,7 @@ def test_drag_and_drop(session,
                        drag_duration):
     drag_target = session.find.css("#dragTarget", all=False)
     initial_rect = drag_target.rect
-    initial_center = get_center(initial_rect)
+    initial_center = get_inview_center(initial_rect, get_viewport_rect(session))
     # Conclude chain with extra move to allow time for last queued
     # coordinate-update of drag_target and to test that drag_target is "dropped".
     mouse_chain \
@@ -125,8 +121,8 @@ def test_drag_and_drop(session,
     # mouseup that ends the drag is at the expected destination
     e = get_events(session)[1]
     assert e["type"] == "mouseup"
-    assert approx(e["pageX"], initial_center["x"] + dx)
-    assert approx(e["pageY"], initial_center["y"] + dy)
+    assert pytest.approx(e["pageX"], initial_center["x"] + dx)
+    assert pytest.approx(e["pageY"], initial_center["y"] + dy)
     # check resulting location of the dragged element
     final_rect = drag_target.rect
     assert initial_rect["x"] + dx == final_rect["x"]
diff --git a/tests/wpt/web-platform-tests/webdriver/tests/actions/mouse_dblclick.py b/tests/wpt/web-platform-tests/webdriver/tests/actions/mouse_dblclick.py
index e9e4c26ad33..bdd39057f5d 100644
--- a/tests/wpt/web-platform-tests/webdriver/tests/actions/mouse_dblclick.py
+++ b/tests/wpt/web-platform-tests/webdriver/tests/actions/mouse_dblclick.py
@@ -1,6 +1,6 @@
 import pytest
 
-from tests.actions.support.mouse import get_center
+from tests.actions.support.mouse import get_inview_center, get_viewport_rect
 from tests.actions.support.refine import get_events, filter_dict
 from tests.support.asserts import assert_move_to_coordinates
 
@@ -63,7 +63,7 @@ def test_dblclick_at_coordinates(dblclick_session, mouse_chain, click_pause):
 
 def test_dblclick_with_pause_after_second_pointerdown(dblclick_session, mouse_chain):
         outer = dblclick_session.find.css("#outer", all=False)
-        center = get_center(outer.rect)
+        center = get_inview_center(outer.rect, get_viewport_rect(dblclick_session))
         mouse_chain \
             .pointer_move(int(center["x"]), int(center["y"])) \
             .click() \
@@ -88,7 +88,7 @@ def test_dblclick_with_pause_after_second_pointerdown(dblclick_session, mouse_ch
 
 def test_no_dblclick(dblclick_session, mouse_chain):
         outer = dblclick_session.find.css("#outer", all=False)
-        center = get_center(outer.rect)
+        center = get_inview_center(outer.rect, get_viewport_rect(dblclick_session))
         mouse_chain \
             .pointer_move(int(center["x"]), int(center["y"])) \
             .click() \
diff --git a/tests/wpt/web-platform-tests/webdriver/tests/actions/pointer_origin.py b/tests/wpt/web-platform-tests/webdriver/tests/actions/pointer_origin.py
new file mode 100644
index 00000000000..cad59f0a13b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/webdriver/tests/actions/pointer_origin.py
@@ -0,0 +1,129 @@
+import pytest
+
+from webdriver import MoveTargetOutOfBoundsException
+
+from tests.actions.support.mouse import get_inview_center, get_viewport_rect
+from tests.support.inline import inline
+
+
+def origin_doc(inner_style, outer_style=""):
+    return inline("""
+      <div id="outer" style="{1}"
+           onmousemove="window.coords = {{x: event.clientX, y: event.clientY}}">
+        <div id="inner" style="{0}"></div>
+      </div>
+    """.format(inner_style, outer_style))
+
+
+def get_click_coordinates(session):
+    return session.execute_script("return window.coords;")
+
+
+def test_viewport_inside(session, mouse_chain):
+    point = {"x": 50, "y": 50}
+
+    session.url = origin_doc("width: 100px; height: 50px; background: green;")
+    mouse_chain \
+        .pointer_move(point["x"], point["y"], origin="viewport") \
+        .perform()
+
+    click_coords = session.execute_script("return window.coords;")
+    assert pytest.approx(click_coords["x"], point["x"])
+    assert pytest.approx(click_coords["y"], point["y"])
+
+
+def test_viewport_outside(session, mouse_chain):
+    with pytest.raises(MoveTargetOutOfBoundsException):
+        mouse_chain \
+            .pointer_move(-50, -50, origin="viewport") \
+            .perform()
+
+
+def test_pointer_inside(session, mouse_chain):
+    start_point = {"x": 50, "y": 50}
+    offset = {"x": 10, "y": 5}
+
+    session.url = origin_doc("width: 100px; height: 50px; background: green;")
+    mouse_chain \
+        .pointer_move(start_point["x"], start_point["y"]) \
+        .pointer_move(offset["x"], offset["y"], origin="pointer") \
+        .perform()
+
+    click_coords = session.execute_script("return window.coords;")
+    assert pytest.approx(click_coords["x"], start_point["x"] + offset["x"])
+    assert pytest.approx(click_coords["y"], start_point["y"] + offset["y"])
+
+
+def test_pointer_outside(session, mouse_chain):
+    with pytest.raises(MoveTargetOutOfBoundsException):
+        mouse_chain \
+            .pointer_move(-50, -50, origin="pointer") \
+            .perform()
+
+
+def test_element_center_point(session, mouse_chain):
+    session.url = origin_doc("width: 100px; height: 50px; background: green;")
+    elem = session.find.css("#inner", all=False)
+    center = get_inview_center(elem.rect, get_viewport_rect(session))
+
+    mouse_chain \
+        .pointer_move(0, 0, origin=elem) \
+        .perform()
+
+    click_coords = get_click_coordinates(session)
+    assert pytest.approx(click_coords["x"], center["x"])
+    assert pytest.approx(click_coords["y"], center["y"])
+
+
+def test_element_center_point_with_offset(session, mouse_chain):
+    session.url = origin_doc("width: 100px; height: 50px; background: green;")
+    elem = session.find.css("#inner", all=False)
+    center = get_inview_center(elem.rect, get_viewport_rect(session))
+
+    mouse_chain \
+        .pointer_move(10, 15, origin=elem) \
+        .perform()
+
+    click_coords = get_click_coordinates(session)
+    assert pytest.approx(click_coords["x"], center["x"] + 10)
+    assert pytest.approx(click_coords["y"], center["y"] + 15)
+
+
+def test_element_in_view_center_point_partly_visible(session, mouse_chain):
+    session.url = origin_doc("""width: 100px; height: 50px; background: green;
+                                position: relative; left: -50px; top: -25px;""")
+    elem = session.find.css("#inner", all=False)
+    center = get_inview_center(elem.rect, get_viewport_rect(session))
+
+    mouse_chain \
+        .pointer_move(0, 0, origin=elem) \
+        .perform()
+
+    click_coords = get_click_coordinates(session)
+    assert pytest.approx(click_coords["x"], center["x"])
+    assert pytest.approx(click_coords["y"], center["y"])
+
+
+def test_element_larger_than_viewport(session, mouse_chain):
+    session.url = origin_doc("width: 300vw; height: 300vh; background: green;")
+    elem = session.find.css("#inner", all=False)
+    center = get_inview_center(elem.rect, get_viewport_rect(session))
+
+    mouse_chain \
+        .pointer_move(0, 0, origin=elem) \
+        .perform()
+
+    click_coords = get_click_coordinates(session)
+    assert pytest.approx(click_coords["x"], center["x"])
+    assert pytest.approx(click_coords["y"], center["y"])
+
+
+def test_element_outside_of_view_port(session, mouse_chain):
+    session.url = origin_doc("""width: 100px; height: 50px; background: green;
+                                position: relative; left: -200px; top: -100px;""")
+    elem = session.find.css("#inner", all=False)
+
+    with pytest.raises(MoveTargetOutOfBoundsException):
+        mouse_chain \
+            .pointer_move(0, 0, origin=elem) \
+            .perform()
diff --git a/tests/wpt/web-platform-tests/webdriver/tests/actions/support/mouse.py b/tests/wpt/web-platform-tests/webdriver/tests/actions/support/mouse.py
index d627ebb9d39..b3672eb213a 100644
--- a/tests/wpt/web-platform-tests/webdriver/tests/actions/support/mouse.py
+++ b/tests/wpt/web-platform-tests/webdriver/tests/actions/support/mouse.py
@@ -1,5 +1,26 @@
-def get_center(rect):
-    return {
-        "x": rect["width"] / 2 + rect["x"],
-        "y": rect["height"] / 2 + rect["y"],
+def get_viewport_rect(session):
+    return session.execute_script("""
+        return {
+          height: window.innerHeight || document.documentElement.clientHeight,
+          width: window.innerWidth || document.documentElement.clientWidth,
+        };
+    """)
+
+
+def get_inview_center(elem_rect, viewport_rect):
+    x = {
+        "left": max(0, min(elem_rect["x"], elem_rect["x"] + elem_rect["width"])),
+        "right": min(viewport_rect["width"], max(elem_rect["x"],
+                                                 elem_rect["x"] + elem_rect["width"])),
+    }
+
+    y = {
+        "top": max(0, min(elem_rect["y"], elem_rect["y"] + elem_rect["height"])),
+        "bottom": min(viewport_rect["height"], max(elem_rect["y"],
+                                                   elem_rect["y"] + elem_rect["height"])),
+    }
+
+    return {
+        "x": (x["left"] + x["right"]) / 2,
+        "y": (y["top"] + y["bottom"]) / 2,
     }
diff --git a/tests/wpt/web-platform-tests/webrtc/RTCPeerConnection-setRemoteDescription-replaceTrack.https.html b/tests/wpt/web-platform-tests/webrtc/RTCPeerConnection-setRemoteDescription-replaceTrack.https.html
index 8a40f9a4456..06408d072af 100644
--- a/tests/wpt/web-platform-tests/webrtc/RTCPeerConnection-setRemoteDescription-replaceTrack.https.html
+++ b/tests/wpt/web-platform-tests/webrtc/RTCPeerConnection-setRemoteDescription-replaceTrack.https.html
@@ -14,7 +14,7 @@
     const caller = new RTCPeerConnection();
     return getUserMediaTracksAndStreams(2)
     .then(t.step_func(([tracks, streams]) => {
-      const sender = caller.addTrack(tracks[0]);
+      const sender = caller.addTrack(tracks[0], streams[0]);
       return sender.replaceTrack(tracks[1])
       .then(t.step_func(() => {
         assert_equals(sender.track, tracks[1]);
@@ -30,7 +30,7 @@
     const caller = new RTCPeerConnection();
     return getUserMediaTracksAndStreams(1)
     .then(t.step_func(([tracks, streams]) => {
-      const sender = caller.addTrack(tracks[0]);
+      const sender = caller.addTrack(tracks[0], streams[0]);
       return sender.replaceTrack(null)
       .then(t.step_func(() => {
         assert_equals(sender.track, null);
@@ -46,7 +46,7 @@
     const caller = new RTCPeerConnection();
     return getUserMediaTracksAndStreams(2)
     .then(t.step_func(([tracks, streams]) => {
-      const sender = caller.addTrack(tracks[0]);
+      const sender = caller.addTrack(tracks[0], streams[0]);
       assert_equals(sender.track, tracks[0]);
       sender.replaceTrack(tracks[1]);
       // replaceTrack() is asynchronous, there should be no synchronously
@@ -64,7 +64,7 @@
     const caller = new RTCPeerConnection();
     return getUserMediaTracksAndStreams(2)
     .then(t.step_func(([tracks, streams]) => {
-      const sender = caller.addTrack(tracks[0]);
+      const sender = caller.addTrack(tracks[0], streams[0]);
       caller.close();
       return sender.replaceTrack(tracks[1])
       .then(t.step_func(() => {
@@ -86,7 +86,7 @@
     const caller = new RTCPeerConnection();
     return getUserMediaTracksAndStreams(2)
     .then(t.step_func(([tracks, streams]) => {
-      const sender = caller.addTrack(tracks[0]);
+      const sender = caller.addTrack(tracks[0], streams[0]);
       caller.removeTrack(sender);
       // replaceTrack() should fail because the sender should be inactive after
       // removeTrack().
@@ -110,7 +110,7 @@
     const caller = new RTCPeerConnection();
     return getUserMediaTracksAndStreams(2)
     .then(t.step_func(([tracks, streams]) => {
-      const sender = caller.addTrack(tracks[0]);
+      const sender = caller.addTrack(tracks[0], streams[0]);
       let p = sender.replaceTrack(tracks[1])
       caller.removeTrack(sender);
       // replaceTrack() should fail because it executes steps in parallel and