Oilpan: Build fix after r177440

Source/core/html/HTMLSourceElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2010 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 41 matching lines @@
     explicit Listener(HTMLSourceElement* element) : m_element(element) { }
     virtual void call() OVERRIDE
     {
         if (m_element)
             m_element->notifyMediaQueryChanged();
     }
 
     void clearElement() { m_element = nullptr; }
     virtual void trace(Visitor* visitor) OVERRIDE
     {
+        visitor->trace(m_element);
         MediaQueryListListener::trace(visitor);
-        visitor->trace(m_element);
     }
 private:
     RawPtrWillBeMember<HTMLSourceElement> m_element;
 };
 
 inline HTMLSourceElement::HTMLSourceElement(Document& document)
     : HTMLElement(sourceTag, document)
     , m_listener(adoptRefWillBeNoop(new Listener(this)))
 {
     WTF_LOG(Media, "HTMLSourceElement::HTMLSourceElement - %p", this);
     ScriptWrappable::init(this);
 }
 
 DEFINE_NODE_FACTORY(HTMLSourceElement)
 
 HTMLSourceElement::~HTMLSourceElement()
 {
     sourceErrorEventSender().cancelEvent(this);
+#if !ENABLE(OILPAN)
     m_listener->clearElement();
+#endif
 }
 
 Node::InsertionNotificationRequest HTMLSourceElement::insertedInto(ContainerNode* insertionPoint)
 {
     HTMLElement::insertedInto(insertionPoint);
     Element* parent = parentElement();
     if (isHTMLMediaElement(parent))
         toHTMLMediaElement(parent)->sourceWasAdded(this);
     if (isHTMLPictureElement(parent))
         toHTMLPictureElement(parent)->sourceOrMediaChanged();
@@ skipping 78 matching lines @@
 
 void HTMLSourceElement::notifyMediaQueryChanged()
 {
     Element* parent = parentElement();
     if (isHTMLPictureElement(parent))
         toHTMLPictureElement(parent)->sourceOrMediaChanged();
 }
 
 void HTMLSourceElement::trace(Visitor* visitor)
 {
-    HTMLElement::trace(visitor);
     visitor->trace(m_mediaQueryList);
     visitor->trace(m_listener);
+    HTMLElement::trace(visitor);
 }
 
 }