[oilpan] Implement accept methods to trace the class hierarchy of SVGElement and all sub-classes.

Source/core/svg/SVGAltGlyphItemElement.h

 /*
  * Copyright (C) 2011 Leo Yang <leoyang@webkit.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 14 matching lines @@
 #include <wtf/Vector.h>
 
 namespace WebCore {
 
 class SVGAltGlyphItemElement: public SVGElement {
 public:
     static PassRefPtr<SVGAltGlyphItemElement> create(const QualifiedName&, const Handle<Document>&);
 
     bool hasValidGlyphElements(Vector<String>& glyphNames) const;
 
+    virtual void accept(Visitor* visitor) const OVERRIDE { SVGElement::accept(visitor); }
+
 private:
     SVGAltGlyphItemElement(const QualifiedName&, const Handle<Document>&);
 };
 
 }
 
 #endif
 #endif