Include Event.h in fewer header files

Source/core/frame/DeviceSingleWindowEventController.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/frame/DeviceSingleWindowEventController.h"
 
 #include "core/dom/Document.h"
+#include "core/events/Event.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/page/Page.h"
 
 namespace WebCore {
 
 DeviceSingleWindowEventController::DeviceSingleWindowEventController(Document& document)
     : DeviceEventControllerBase(document.page())
     , DOMWindowLifecycleObserver(document.domWindow())
     , m_needsCheckingNullEvents(true)
     , m_document(document)
@@ skipping 45 matching lines @@
     m_hasEventListener = false;
 }
 
 void DeviceSingleWindowEventController::didRemoveAllEventListeners(LocalDOMWindow*)
 {
     stopUpdating();
     m_hasEventListener = false;
 }
 
 } // namespace WebCore