Implement matching part of ::slotted() pseudo element

third_party/WebKit/Source/core/css/SelectorFilter.cpp

Index: third_party/WebKit/Source/core/css/SelectorFilter.cpp
diff --git a/third_party/WebKit/Source/core/css/SelectorFilter.cpp b/third_party/WebKit/Source/core/css/SelectorFilter.cpp
index 82863003a1d44c11bb03945fe377ea5c63303b56..8f742992eaacf4a0c2abcb4d07071fcc6a05300f 100644
--- a/third_party/WebKit/Source/core/css/SelectorFilter.cpp
+++ b/third_party/WebKit/Source/core/css/SelectorFilter.cpp
@@ -134,7 +134,7 @@ void SelectorFilter::collectIdentifierHashes(const CSSSelector& selector, unsign
     unsigned* hash = identifierHashes;
     unsigned* end = identifierHashes + maximumIdentifierCount;
     CSSSelector::Relation relation = selector.relation();
-    bool relationIsAffectedByPseudoContent = selector.relationIsAffectedByPseudoContent();
+    bool relationIsAffectedByPseudoContentOrSlotted = selector.relationIsAffectedByPseudoContent() || selector.pseudoType() == CSSSelector::PseudoSlotted;

[rune, 2016/01/20 12:53:32]

I think this code is a bit more advanced than it needs to. Here we could have
done an early return like this:

if (selector.relationIsAffectedByPseudoContent())
    return;

[kochi, 2016/01/21 05:09:37]

Done.

 
     // Skip the topmost selector. It is handled quickly by the rule hashes.
     bool skipOverSubselectors = true;
@@ -151,7 +151,8 @@ void SelectorFilter::collectIdentifierHashes(const CSSSelector& selector, unsign
             break;
         case CSSSelector::Descendant:
         case CSSSelector::Child:
-            if (relationIsAffectedByPseudoContent) {
+        case CSSSelector::ShadowSlot:
+            if (relationIsAffectedByPseudoContentOrSlotted) {
                 // Disable fastRejectSelector.
                 *identifierHashes = 0;
                 return;
@@ -162,14 +163,11 @@ void SelectorFilter::collectIdentifierHashes(const CSSSelector& selector, unsign
             skipOverSubselectors = false;
             collectDescendantSelectorIdentifierHashes(*current, hash);
             break;
-        case CSSSelector::ShadowSlot:
-            // TODO(kochi): Add this in later CL.
-            break;
         }
         if (hash == end)
             return;
         relation = current->relation();
-        relationIsAffectedByPseudoContent = current->relationIsAffectedByPseudoContent();
+        relationIsAffectedByPseudoContentOrSlotted = current->relationIsAffectedByPseudoContent() || current->pseudoType() == CSSSelector::PseudoSlotted;

[rune, 2016/01/20 12:53:32]

This can be replaced with:

if (current->relationIsAffectedByPseudoContent()) {
    *identifierHashes = 0;
    return;
}

[kochi, 2016/01/21 05:09:37]

Done.

     }
     *hash = 0;
 }