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

Source/core/page/EventSource.cpp

 /*
  * Copyright (C) 2009, 2012 Ericsson AB. All rights reserved.
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2011, Code Aurora Forum. 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
@@ skipping 406 matching lines @@
             }
         }
     }
 }
 
 void EventSource::stop()
 {
     close();
 }
 
-PassRefPtr<MessageEvent> EventSource::createMessageEvent()
+PassRefPtrWillBeRawPtr<MessageEvent> EventSource::createMessageEvent()
 {
-    RefPtr<MessageEvent> event = MessageEvent::create();
+    RefPtrWillBeRawPtr<MessageEvent> event = MessageEvent::create();
     event->initMessageEvent(m_eventName.isEmpty() ? EventTypeNames::message : m_eventName, false, false, SerializedScriptValue::create(String(m_data)), m_eventStreamOrigin, m_lastEventId, 0, nullptr);
     m_data.clear();
     return event.release();
 }
 
 } // namespace WebCore