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..5048296531254421fd45ad136a20ea558870ff88 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -78,24 +78,21 @@ StyleEngine::~StyleEngine()
 {
 }
 
+#if !ENABLE(OILPAN)
 void StyleEngine::detachFromDocument()
 {
     // 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();

[Mads Ager (chromium), 2014/05/05 13:06:40]

Erik points out that removing this is probably unsafe. He is right, however,
Gustav has a change ready that will make it safe and we will see if we can land
our changes together tomorrow morning. :)

[haraken, 2014/05/06 04:20:16]

Yeah, this looks unsafe. Want to look at the change from Gustav :)

[Erik Corry, 2014/05/06 08:29:40]

As discussed offline this is still needed somehow.  Gustav says his change will
fix this.

-#if !ENABLE(OILPAN)
         if (m_resolver)
             m_fontSelector->unregisterForInvalidationCallbacks(m_resolver.get());
-#endif
     }
 
     // Decrement reference counts for things we could be keeping alive.
@@ -103,6 +100,7 @@ void StyleEngine::detachFromDocument()
     m_resolver.clear();
     m_styleSheetCollectionMap.clear();

[haraken, 2014/05/06 04:20:16]

Just to confirm: The line 99 - 101 was not needed in oilpan builds even before
this CL, right?

[Mads Ager (chromium), 2014/05/06 08:26:00]

I think that is right. In any case Gustav has a change out that makes sure that
this method is not needed with Oilpan.

 }
+#endif
 
 inline Document* StyleEngine::master()
 {