Make ::slotted() never match <slot> elements.

According to the css-scoping spec, ::slotted() matches flattened slotables. Slot elements which are assigned to other slots are not part of the flattened slotables. The test currently fails because slots are not included in the flat tree. Bug: 660265 Change-Id: Ifbcb03d3212db59d762d173a221382ed79ccbd0e Reviewed-on: https://chromium-review.googlesource.com/887950Reviewed-by: Hayato Ito <hayato@chromium.org> Commit-Queue: Rune Lillesveen <futhark@chromium.org> Cr-Commit-Position: refs/heads/master@{#532335}

Make ::slotted() never match <slot> elements.
According to the css-scoping spec, ::slotted() matches flattened slotables. Slot elements which are assigned to other slots are not part of the flattened slotables. The test currently fails because slots are not included in the flat tree. Bug: 660265 Change-Id: Ifbcb03d3212db59d762d173a221382ed79ccbd0e Reviewed-on: https://chromium-review.googlesource.com/887950Reviewed-by: Hayato Ito <hayato@chromium.org> Commit-Queue: Rune Lillesveen <futhark@chromium.org> Cr-Commit-Position: refs/heads/master@{#532335}
716357ac · Rune Lillesveen · Commit Bot · 58d554bd · 716357ac · 716357ac
Commit 716357ac authored Jan 29, 2018 by Rune Lillesveen Committed by Commit Bot Jan 29, 2018
3 changed files
--- a/third_party/WebKit/LayoutTests/TestExpectations
+++ b/third_party/WebKit/LayoutTests/TestExpectations
@@ -920,6 +920,7 @@ crbug.com/505364 external/wpt/shadow-dom/untriaged/elements-and-dom-objects/exte
 crbug.com/505364 external/wpt/css/css-scoping/css-scoping-shadow-slot-display-override.html [ Failure ]
 crbug.com/505364 external/wpt/css/css-scoping/css-scoping-shadow-slot-style.html [ Failure ]
 crbug.com/505364 external/wpt/css/css-scoping/css-scoping-shadow-nested-slot-display-override.html [ Failure ]
+crbug.com/505364 external/wpt/css/css-scoping/slotted-slot.html [ Failure ]
 crbug.com/552494 scrollbars/overflow-scrollbar-combinations.html [ Pass Failure ]
 crbug.com/552494 virtual/prefer_compositing_to_lcd_text/scrollbars/overflow-scrollbar-combinations.html [ Pass Failure ]

--- a/third_party/WebKit/LayoutTests/external/wpt/css/css-scoping/slotted-slot.html
+++ b/third_party/WebKit/LayoutTests/external/wpt/css/css-scoping/slotted-slot.html
+<!DOCTYPE html>
+<title>CSS Test: ::slotted() not matching slot elements</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" style="color:green">This text should be green.</div>
+<script>
+  test(() => {
+    let root = host.attachShadow({mode:"open"});
+    root.innerHTML = '<div><slot id="slot"></slot><div>';
+    let innerHost = root.firstChild;
+    let innerRoot = innerHost.attachShadow({mode:"open"});
+    innerRoot.innerHTML = "<style>::slotted(#slot){color:red}</style><slot></slot>";
+    assert_equals(getComputedStyle(root.querySelector("#slot")).color, "rgb(0, 128, 0)");
+  }, "Check that ::slotted does not match slot elements");
+</script>
--- a/third_party/WebKit/Source/core/css/SelectorChecker.cpp
+++ b/third_party/WebKit/Source/core/css/SelectorChecker.cpp
@@ -504,6 +504,10 @@ SelectorChecker::MatchStatus SelectorChecker::MatchForRelation(
    }
    case CSSSelector::kShadowSlot: {
+      if (IsHTMLSlotElement(context.element) &&
+          ToHTMLSlotElement(context.element)->SupportsAssignment()) {
+        return kSelectorFailsCompletely;
+      }
      const HTMLSlotElement* slot = FindSlotElementInScope(context);
      if (!slot)
        return kSelectorFailsCompletely;