Add [WillBeGarbageCollected] to Event.idl

Source/core/events/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 116 matching lines @@
     , m_dataAsArrayBuffer(data)
     , m_origin(origin)
 {
     ScriptWrappable::init(this);
 }
 
 MessageEvent::~MessageEvent()
 {
 }
 
-PassRefPtr<MessageEvent> MessageEvent::create(const AtomicString& type, const MessageEventInit& initializer, ExceptionState& exceptionState)
+PassRefPtrWillBeRawPtr<MessageEvent> MessageEvent::create(const AtomicString& type, const MessageEventInit& initializer, ExceptionState& exceptionState)
 {
     if (initializer.source.get() && !isValidSource(initializer.source.get())) {
         exceptionState.throwTypeError("The optional 'source' property is neither a Window nor MessagePort.");
         return nullptr;
     }
-    return adoptRef(new MessageEvent(type, initializer));
+    return adoptRefCountedWillBeRefCountedGarbageCollected(new MessageEvent(type, initializer));
 }
 
 void MessageEvent::initMessageEvent(const AtomicString& type, bool canBubble, bool cancelable, const String& origin, const String& lastEventId, DOMWindow* source, PassOwnPtr<MessagePortArray> ports)
 {
     if (dispatched())
         return;
 
     initEvent(type, canBubble, cancelable);
 
     m_dataType = DataTypeScriptValue;
@@ skipping 30 matching lines @@
 {
     m_ports = MessagePort::entanglePorts(*context, m_channels.release());
 }
 
 void MessageEvent::trace(Visitor* visitor)
 {
     Event::trace(visitor);
 }
 
 } // namespace WebCore