Include Event.h in fewer header files

Source/modules/mediastream/MediaStreamTrack.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  * Copyright (C) 2011 Ericsson AB. 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 11 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "modules/mediastream/MediaStreamTrack.h"
 
 #include "bindings/v8/ExceptionMessages.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContext.h"
+#include "core/events/Event.h"
 #include "modules/mediastream/MediaStream.h"
 #include "modules/mediastream/MediaStreamTrackSourcesCallback.h"
 #include "modules/mediastream/MediaStreamTrackSourcesRequestImpl.h"
 #include "platform/mediastream/MediaStreamCenter.h"
 #include "platform/mediastream/MediaStreamComponent.h"
 #include "public/platform/WebSourceInfo.h"
 
 namespace WebCore {
 
 PassRefPtrWillBeRawPtr<MediaStreamTrack> MediaStreamTrack::create(ExecutionContext* context, MediaStreamComponent* component)
@@ skipping 179 matching lines @@
     return ActiveDOMObject::executionContext();
 }
 
 void MediaStreamTrack::trace(Visitor* visitor)
 {
     visitor->trace(m_registeredMediaStreams);
     EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace WebCore