Get rid of TreeBoundaryCrossingRules.

Source/core/css/resolver/ScopedStyleResolver.cpp

Index: Source/core/css/resolver/ScopedStyleResolver.cpp
diff --git a/Source/core/css/resolver/ScopedStyleResolver.cpp b/Source/core/css/resolver/ScopedStyleResolver.cpp
index 0b84c3a1d12cf448ad8fdb4eac51cd0c4d033e66..e64a1c1e5dad177cd470d821f206c0761df7e1c0 100644
--- a/Source/core/css/resolver/ScopedStyleResolver.cpp
+++ b/Source/core/css/resolver/ScopedStyleResolver.cpp
@@ -46,6 +46,12 @@
 
 namespace blink {
 
+ScopedStyleResolver::~ScopedStyleResolver()
+{
+    if (m_treeBoundaryCrossingRuleSet)
+        treeScope().document().styleEngine().removeTreeBoundaryCrossingScope();
+}
+
 TreeScope* ScopedStyleResolver::treeScopeFor(Document& document, const CSSStyleSheet* sheet)
 {
     ASSERT(sheet);
@@ -131,6 +137,7 @@ void ScopedStyleResolver::resetAuthorStyle()
     m_authorStyleSheets.clear();
     m_keyframesRuleMap.clear();
     m_treeBoundaryCrossingRuleSet = nullptr;
+    treeScope().document().styleEngine().removeTreeBoundaryCrossingScope();
 }
 
 StyleRuleKeyframes* ScopedStyleResolver::keyframeStylesForAnimation(const StringImpl* animationName)
@@ -188,11 +195,19 @@ void ScopedStyleResolver::collectMatchingShadowHostRules(ElementRuleCollector& c
 
 void ScopedStyleResolver::collectMatchingTreeBoundaryCrossingRules(ElementRuleCollector& collector, bool includeEmptyRules, CascadeOrder cascadeOrder)
 {
+    if (!m_treeBoundaryCrossingRuleSet)
+        return;
+
+    ASSERT(!collector.scopeContainsLastMatchedElement());
+    collector.setScopeContainsLastMatchedElement(true);
+
     RuleRange ruleRange = collector.matchedResult().ranges.authorRuleRange();
     for (const auto& rules : *m_treeBoundaryCrossingRuleSet) {
         MatchRequest request(rules->m_ruleSet.get(), includeEmptyRules, &treeScope().rootNode(), rules->m_parentStyleSheet, rules->m_parentIndex);
         collector.collectMatchingRules(request, ruleRange, cascadeOrder, true);
     }
+
+    collector.setScopeContainsLastMatchedElement(false);
 }
 
 void ScopedStyleResolver::matchPageRules(PageRuleCollector& collector)
@@ -243,7 +258,7 @@ void ScopedStyleResolver::addTreeBoundaryCrossingRules(const RuleSet& authorRule
 
     if (!m_treeBoundaryCrossingRuleSet) {
         m_treeBoundaryCrossingRuleSet = adoptPtrWillBeNoop(new CSSStyleSheetRuleSubSet());
-        treeScope().document().styleResolver()->addTreeBoundaryCrossingScope(treeScope().rootNode());
+        treeScope().document().styleEngine().addTreeBoundaryCrossingScope();
     }
 
     m_treeBoundaryCrossingRuleSet->append(RuleSubSet::create(parentStyleSheet, sheetIndex, ruleSetForScope.release()));