Oilpan: Replace RefPtr to Node in MutationObserver-related classes with Oilpan transition types.

Source/core/dom/MutationObserverRegistration.cpp

 /*
  * Copyright (C) 2011 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 63 matching lines @@
 
 void MutationObserverRegistration::observedSubtreeNodeWillDetach(Node& node)
 {
     if (!isSubtree())
         return;
 
     node.registerTransientMutationObserver(this);
     m_observer->setHasTransientRegistration();
 
     if (!m_transientRegistrationNodes) {
-        m_transientRegistrationNodes = adoptPtr(new NodeHashSet);
+        m_transientRegistrationNodes = adoptPtrWillBeNoop(new NodeHashSet);
 
         ASSERT(m_registrationNode);
         ASSERT(!m_registrationNodeKeepAlive);
         m_registrationNodeKeepAlive = PassRefPtrWillBeRawPtr<Node>(m_registrationNode.get()); // Balanced in clearTransientRegistrations.
     }
     m_transientRegistrationNodes->add(&node);
 }
 
 void MutationObserverRegistration::clearTransientRegistrations()
 {
@@ skipping 44 matching lines @@
         return;
     for (NodeHashSet::const_iterator iter = m_transientRegistrationNodes->begin(); iter != m_transientRegistrationNodes->end(); ++iter)
         nodes.add(iter->get());
 }
 
 void MutationObserverRegistration::trace(Visitor* visitor)
 {
     visitor->trace(m_observer);
     visitor->trace(m_registrationNode);
     visitor->trace(m_registrationNodeKeepAlive);
+#if ENABLE(OILPAN)
+    visitor->trace(m_transientRegistrationNodes);
+#endif
 }
 
 } // namespace WebCore