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

Source/core/dom/Entity.h

 /*
  * Copyright (C) 2000 Peter Kelly (pmk@post.com)
  * Copyright (C) 2006, 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 15 matching lines @@
 
 namespace WebCore {
 
 // FIXME: This abstract class is only here so that the JavaScript and bindings can continue to be compiled.
 class Entity : public ContainerNode {
 public:
     String publicId() const { ASSERT_NOT_REACHED(); return String(); }
     String systemId() const { ASSERT_NOT_REACHED(); return String(); }
     String notationName() const { ASSERT_NOT_REACHED(); return String(); }
 
+    void acceptHeapVisitor(Visitor* visitor) const OVERRIDE
+    {
+        ContainerNode::acceptHeapVisitor(visitor);
+    }
+
 private:
     Entity() : ContainerNode(nullptr)
     {
         ScriptWrappable::init(this);
     }
 };
 
 } //namespace
 
 #endif