Remove the CSSOM.

sky/engine/core/frame/LocalDOMWindow.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation 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.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 23 matching lines @@
 #include "sky/engine/core/frame/FrameDestructionObserver.h"
 #include "sky/engine/platform/LifecycleContext.h"
 #include "sky/engine/platform/Supplementable.h"
 #include "sky/engine/platform/heap/Handle.h"
 
 #include "sky/engine/wtf/Forward.h"
 
 namespace blink {
 
 class Application;
-class CSSRuleList;
 class CSSStyleDeclaration;
 class Console;
 class DOMSelection;
 class DOMURL;
 class DOMWindowCSS;
 class DOMWindowEventQueue;
 class DOMWindowLifecycleNotifier;
 class DOMWindowProperty;
 class Database;
 class DatabaseCallback;
@@ skipping 196 matching lines @@
 
     mutable RefPtr<DOMWindowCSS> m_css;
 
     RefPtr<DOMWindowEventQueue> m_eventQueue;
     RefPtr<SerializedScriptValue> m_pendingStateObject;
 };
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_FRAME_LOCALDOMWINDOW_H_