Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/StyleEngine.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 62 matching lines @@
     , m_fontSelector(document.frame() ? CSSFontSelector::create(&document) : nullptr)
 {
 }
 
 StyleEngine::~StyleEngine()
 {
 }
 
 void StyleEngine::detachFromDocument()
 {
+#if !ENABLE(OILPAN)
     // Cleanup is performed eagerly when the StyleEngine is removed from the
     // document. The StyleEngine is unreachable after this, since only the
     // document has a reference to it.
 #if !ENABLE(OILPAN)
     for (unsigned i = 0; i < m_injectedAuthorStyleSheets.size(); ++i)
         m_injectedAuthorStyleSheets[i]->clearOwnerNode();
     for (unsigned i = 0; i < m_authorStyleSheets.size(); ++i)
         m_authorStyleSheets[i]->clearOwnerNode();
 #endif
 
     if (m_fontSelector) {
         m_fontSelector->clearDocument();
-#if !ENABLE(OILPAN)
         if (m_resolver)
             m_fontSelector->unregisterForInvalidationCallbacks(m_resolver.get());
-#endif
     }
 
     // Decrement reference counts for things we could be keeping alive.
     m_fontSelector.clear();
     m_resolver.clear();
     m_styleSheetCollectionMap.clear();
+#endif
 }
 
 inline Document* StyleEngine::master()
 {
     if (isMaster())
         return &m_document;
     HTMLImportsController* import = m_document.importsController();
     if (!import) // Document::import() can return null while executing its destructor.
         return 0;
     return import->master();
@@ skipping 522 matching lines @@
     visitor->trace(m_authorStyleSheets);
     visitor->trace(m_documentStyleSheetCollection);
     visitor->trace(m_styleSheetCollectionMap);
     visitor->trace(m_resolver);
     visitor->trace(m_fontSelector);
     visitor->trace(m_textToSheetCache);
     visitor->trace(m_sheetToTextCache);
 }
 
 }