Add support for new CSS ::slotted() pseudo element

third_party/WebKit/Source/core/css/resolver/ScopedStyleResolver.cpp

Index: third_party/WebKit/Source/core/css/resolver/ScopedStyleResolver.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/ScopedStyleResolver.cpp b/third_party/WebKit/Source/core/css/resolver/ScopedStyleResolver.cpp
index 101fcdf190ab495b588ebd6a6d3e8af44584c9dc..356f29542fa275d1efdbca8d97b1a2989a7f2d10 100644
--- a/third_party/WebKit/Source/core/css/resolver/ScopedStyleResolver.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/ScopedStyleResolver.cpp
@@ -206,7 +206,8 @@ static void addRules(RuleSet* ruleSet, const WillBeHeapVector<MinimalRuleData>&
 void ScopedStyleResolver::addTreeBoundaryCrossingRules(const RuleSet& authorRules, CSSStyleSheet* parentStyleSheet, unsigned sheetIndex)
 {
     bool isDocumentScope = treeScope().rootNode().isDocumentNode();
-    if (authorRules.deepCombinatorOrShadowPseudoRules().isEmpty() && (isDocumentScope || authorRules.shadowDistributedRules().isEmpty()))
+    if (authorRules.deepCombinatorOrShadowPseudoRules().isEmpty()
+        && (isDocumentScope || (authorRules.shadowDistributedRules().isEmpty() && authorRules.shadowSlottedRules().isEmpty())))
         return;
 
     if (!authorRules.deepCombinatorOrShadowPseudoRules().isEmpty())
@@ -215,8 +216,10 @@ void ScopedStyleResolver::addTreeBoundaryCrossingRules(const RuleSet& authorRule
     OwnPtrWillBeRawPtr<RuleSet> ruleSetForScope = RuleSet::create();
     addRules(ruleSetForScope.get(), authorRules.deepCombinatorOrShadowPseudoRules());
 
-    if (!isDocumentScope)
+    if (!isDocumentScope) {
         addRules(ruleSetForScope.get(), authorRules.shadowDistributedRules());
+        addRules(ruleSetForScope.get(), authorRules.shadowSlottedRules());
+    }
 
     if (!m_treeBoundaryCrossingRuleSet) {
         m_treeBoundaryCrossingRuleSet = adoptPtrWillBeNoop(new CSSStyleSheetRuleSubSet());