Oilpan: add [WillBeGarbageCollected] for Node.

Source/core/loader/SinkDocument.h

 /*
  * Copyright (C) 2010 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 14 matching lines @@
 
 #ifndef SinkDocument_h
 #define SinkDocument_h
 
 #include "core/html/HTMLDocument.h"
 
 namespace WebCore {
 
 class SinkDocument FINAL : public HTMLDocument {
 public:
-    static PassRefPtr<SinkDocument> create(const DocumentInit& initializer = DocumentInit())
+    static PassRefPtrWillBeRawPtr<SinkDocument> create(const DocumentInit& initializer = DocumentInit())
     {
-        return adoptRef(new SinkDocument(initializer));
+        return adoptRefWillBeRefCountedGarbageCollected(new SinkDocument(initializer));
     }
 
 private:
     SinkDocument(const DocumentInit&);
 
     virtual PassRefPtr<DocumentParser> createParser() OVERRIDE;
 };
 
 
 }; // namespace WebCore
 
 #endif // SinkDocument_h