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

Source/core/dom/ProcessingInstruction.cpp

 /*
  * Copyright (C) 2000 Peter Kelly (pmk@post.com)
  * Copyright (C) 2006, 2008, 2009 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 292 matching lines @@
     if (document()->renderer())
         document()->styleResolverChanged(DeferRecalcStyle);
 }
 
 void ProcessingInstruction::finishParsingChildren()
 {
     m_createdByParser = false;
     Node::finishParsingChildren();
 }
 
+void ProcessingInstruction::acceptHeapVisitor(Visitor* visitor) const
+{
+    Node::acceptHeapVisitor(visitor);
+}
+
 } // namespace