Oilpan: Replace most of RefPtrs for Event objects with oilpan's transition types

Source/modules/mediasource/WebKitSourceBufferList.cpp

 /*
  * Copyright (C) 2012 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 68 matching lines @@
     for (size_t i = 0; i < m_list.size(); ++i)
         m_list[i]->removedFromMediaSource();
     m_list.clear();
     createAndFireEvent(EventTypeNames::webkitremovesourcebuffer);
 }
 
 void WebKitSourceBufferList::createAndFireEvent(const AtomicString& eventName)
 {
     ASSERT(m_asyncEventQueue);
 
-    RefPtr<Event> event = Event::create(eventName);
+    RefPtrWillBeRawPtr<Event> event = Event::create(eventName);
     event->setTarget(this);
 
     m_asyncEventQueue->enqueueEvent(event.release());
 }
 
 const AtomicString& WebKitSourceBufferList::interfaceName() const
 {
     return EventTargetNames::WebKitSourceBufferList;
 }
 
 ExecutionContext* WebKitSourceBufferList::executionContext() const
 {
     return m_executionContext;
 }
 
 void WebKitSourceBufferList::trace(Visitor* visitor)
 {
     visitor->trace(m_list);
 }
 
 } // namespace WebCore