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

Source/core/html/HTMLAudioElement.cpp

 /*
  * Copyright (C) 2007, 2010, 2011, 2012, 2013 Apple 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 40 matching lines @@
     RefPtr<HTMLAudioElement> audio = adoptRef(new HTMLAudioElement(audioTag, document, false));
     audio->setPreload("auto");
     if (!src.isNull()) {
         audio->setSrc(src);
         audio->scheduleDelayedAction(HTMLMediaElement::LoadMediaResource);
     }
     audio->suspendIfNeeded();
     return audio.release();
 }
 
+void HTMLAudioElement::acceptHeapVisitor(Visitor* visitor) const
+{
+    HTMLMediaElement::acceptHeapVisitor(visitor);
 }
+
+}