[oilpan] The Node hierarchy should have correct accept method chains

Source/core/html/MediaDocument.h

 /*
  * Copyright (C) 2008,2009 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 22 matching lines @@
 class MediaDocument : public HTMLDocument {
 public:
     static PassRefPtr<MediaDocument> create(Frame* frame, const KURL& url)
     {
         return adoptRef(new MediaDocument(frame, url));
     }
     virtual ~MediaDocument();
 
     void mediaElementSawUnsupportedTracks();
 
+    virtual void acceptHeapVisitor(Visitor*) const OVERRIDE;
+
 private:
     MediaDocument(Frame*, const KURL&);
 
     virtual bool isMediaDocument() const { return true; }        
     virtual PassRefPtr<DocumentParser> createParser();
 
     virtual void defaultEventHandler(Event*);
 
     void replaceMediaElementTimerFired(Timer<MediaDocument>*);
 
@@ skipping 21 matching lines @@
 {
     return toMediaDocument(Handle<const Document>(document));
 }
 
 // This will catch anyone doing an unnecessary cast.
 void toMediaDocument(const MediaDocument*);
 
 }
 
 #endif