Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/StyleEngine.cpp

Index: Source/core/dom/StyleEngine.cpp
diff --git a/Source/core/dom/StyleEngine.cpp b/Source/core/dom/StyleEngine.cpp
index 0ba45539df989ad6ed7c39af7de8de08a9ed8e75..e8e4bac633a62838ede86a74fed312c4e76877c2 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -80,6 +80,7 @@ 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.
@@ -92,16 +93,15 @@ void StyleEngine::detachFromDocument()
 
     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()