Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/DocumentStyleSheetCollector.h

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 29 matching lines @@
 class StyleSheetCollection;
 
 class DocumentStyleSheetCollector {
     // This class contains references to two on-heap collections, therefore
     // it's unhealthy to have it anywhere but on the stack, where stack
     // scanning will keep them alive.
     STACK_ALLOCATED();
 public:
     friend class ImportedDocumentStyleSheetCollector;
 
-    DocumentStyleSheetCollector(WillBeHeapVector<RefPtrWillBeMember<StyleSheet> >& sheetsForList, WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet> >& activeList, HashSet<Document*>&);
+    DocumentStyleSheetCollector(WillBeHeapVector<RefPtrWillBeMember<StyleSheet> >& sheetsForList, WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet> >& activeList, WillBeHeapHashSet<RawPtrWillBeMember<Document> >&);
     ~DocumentStyleSheetCollector();
 
     void appendActiveStyleSheets(const WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet> >&);
     void appendActiveStyleSheet(CSSStyleSheet*);
     void appendSheetForList(StyleSheet*);
 
     bool hasVisited(Document* document) const { return m_visitedDocuments.contains(document); }
     void willVisit(Document* document) { m_visitedDocuments.add(document); }
 
 private:
     WillBeHeapVector<RefPtrWillBeMember<StyleSheet> >& m_styleSheetsForStyleSheetList;
     WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet> >& m_activeAuthorStyleSheets;
-    HashSet<Document*>& m_visitedDocuments;
+    WillBeHeapHashSet<RawPtrWillBeMember<Document> >& m_visitedDocuments;
 };
 
 class ActiveDocumentStyleSheetCollector FINAL : public DocumentStyleSheetCollector {
 public:
     ActiveDocumentStyleSheetCollector(StyleSheetCollection&);
 private:
-    HashSet<Document*> m_visitedDocuments;
+    WillBeHeapHashSet<RawPtrWillBeMember<Document> > m_visitedDocuments;
 };
 
 class ImportedDocumentStyleSheetCollector FINAL : public DocumentStyleSheetCollector {
 public:
     ImportedDocumentStyleSheetCollector(DocumentStyleSheetCollector&, WillBeHeapVector<RefPtrWillBeMember<StyleSheet> >&);
 };
 
 } // namespace WebCore
 
 #endif // DocumentStyleSheetCollector_h