MessageEvent constructor should accept a MessagePort as source

Source/core/dom/MessageEvent.cpp

 /*
  * Copyright (C) 2007 Henry Mason (hmason@mac.com)
  * Copyright (C) 2003, 2005, 2006, 2007, 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
@@ skipping 35 matching lines @@
     : m_dataType(DataTypeScriptValue)
 {
     ScriptWrappable::init(this);
 }
 
 MessageEvent::MessageEvent(const AtomicString& type, const MessageEventInit& initializer)
     : Event(type, initializer)
     , m_dataType(DataTypeScriptValue)
     , m_origin(initializer.origin)
     , m_lastEventId(initializer.lastEventId)
-    , m_source(initializer.source)
+    , m_source(isValidSource(initializer.source.get()) ? initializer.source : 0)
     , m_ports(adoptPtr(new MessagePortArray(initializer.ports)))
 {
     ScriptWrappable::init(this);
     ASSERT(isValidSource(m_source.get()));
 }
 
 MessageEvent::MessageEvent(const String& origin, const String& lastEventId, PassRefPtr<EventTarget> source, PassOwnPtr<MessagePortArray> ports)
     : Event(eventNames().messageEvent, false, false)
     , m_dataType(DataTypeScriptValue)
     , m_origin(origin)
@@ skipping 85 matching lines @@
     if (m_dataAsSerializedScriptValue)
         m_dataAsSerializedScriptValue->registerMemoryAllocatedWithCurrentScriptContext();
 }
 
 const AtomicString& MessageEvent::interfaceName() const
 {
     return eventNames().interfaceForMessageEvent;
 }
 
 } // namespace WebCore