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

Source/core/dom/MessagePort.cpp

 /*
  * Copyright (C) 2008 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 179 matching lines @@
         return;
 
     RefPtr<SerializedScriptValue> message;
     OwnPtr<MessagePortChannelArray> channels;
     while (m_entangledChannel && tryGetMessageFrom(*m_entangledChannel, message, channels)) {
         // close() in Worker onmessage handler should prevent next message from dispatching.
         if (executionContext()->isWorkerGlobalScope() && toWorkerGlobalScope(executionContext())->isClosing())
             return;
 
         OwnPtr<MessagePortArray> ports = MessagePort::entanglePorts(*executionContext(), channels.release());
-        RefPtr<Event> evt = MessageEvent::create(ports.release(), message.release());
+        RefPtrWillBeRawPtr<Event> evt = MessageEvent::create(ports.release(), message.release());
 
         dispatchEvent(evt.release(), ASSERT_NO_EXCEPTION);
     }
 }
 
 bool MessagePort::hasPendingActivity() const
 {
     // The spec says that entangled message ports should always be treated as if they have a strong reference.
     // We'll also stipulate that the queue needs to be open (if the app drops its reference to the port before start()-ing it, then it's not really entangled as it's unreachable).
     return m_started && isEntangled();
@@ skipping 39 matching lines @@
     OwnPtr<MessagePortArray> portArray = adoptPtr(new MessagePortArray(channels->size()));
     for (unsigned i = 0; i < channels->size(); ++i) {
         RefPtr<MessagePort> port = MessagePort::create(context);
         port->entangle((*channels)[i].release());
         (*portArray)[i] = port.release();
     }
     return portArray.release();
 }
 
 } // namespace WebCore