Prefer to forward-declare GraphicsContext in headers.

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * 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.
@@ skipping 71 matching lines @@
 #include "core/rendering/RenderTextControlSingleLine.h"
 #include "core/rendering/RenderView.h"
 #include "core/rendering/RenderWidget.h"
 #include "core/rendering/style/RenderStyle.h"
 #include "core/svg/SVGDocumentExtensions.h"
 #include "core/svg/SVGUseElement.h"
 #include "platform/PlatformGestureEvent.h"
 #include "platform/PlatformKeyboardEvent.h"
 #include "platform/PlatformTouchEvent.h"
 #include "platform/PlatformWheelEvent.h"
+#include "platform/TraceEvent.h"
 #include "platform/WindowsKeyboardCodes.h"
 #include "platform/geometry/FloatPoint.h"
 #include "platform/graphics/Image.h"
 #include "platform/heap/Handle.h"
 #include "platform/scroll/ScrollAnimator.h"
 #include "platform/scroll/Scrollbar.h"
 #include "wtf/Assertions.h"
 #include "wtf/CurrentTime.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/TemporaryChange.h"
@@ skipping 3650 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace WebCore