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

Source/core/html/HTMLDocument.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * 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.
  *
@@ skipping 396 matching lines @@
     // We've long had a comment saying that IE doesn't support this.
     // But I do see it in the documentation for Mozilla.
 }
 
 bool HTMLDocument::isFrameSet() const
 {
     HTMLElement* bodyElement = body();
     return bodyElement && bodyElement->hasTagName(framesetTag);
 }
 
+void HTMLDocument::acceptHeapVisitor(Visitor* visitor) const
+{
+    Document::acceptHeapVisitor(visitor);
 }
+
+}