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

Source/core/html/shadow/ClearButtonElement.h

 /*
  * Copyright (C) 2013 Google 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 27 matching lines @@
         virtual ~ClearButtonOwner() { }
         virtual void focusAndSelectClearButtonOwner() = 0;
         virtual bool shouldClearButtonRespondToMouseEvents() = 0;
         virtual void clearValue() = 0;
     };
 
     static PassRefPtr<ClearButtonElement> create(Handle<Document>, ClearButtonOwner&);
     void releaseCapture();
     void removeClearButtonOwner() { m_clearButtonOwner = 0; }
 
+    virtual void acceptHeapVisitor(Visitor*) const OVERRIDE;
+
 private:
     ClearButtonElement(Handle<Document>, ClearButtonOwner&);
     virtual void detach();
     virtual bool isMouseFocusable() const { return false; }
     virtual void defaultEventHandler(Event*);
 
     ClearButtonOwner* m_clearButtonOwner;
     bool m_capturing;
 };
 
 } // namespace
 
 #endif // ClearButtonElement_h