Remove Widget's dependency upon its own inheritor aka ScrollView. This was nasty from an OO design…

Source/platform/scroll/ScrollbarThemeClient.h

 /*
  * Copyright (C) 2012 Google 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 17 matching lines @@
 
 #include "platform/geometry/IntPoint.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/Vector.h"
 
 namespace WebCore {
 
-class ScrollView;
+class Widget;
 
 class ScrollbarThemeClient {
 public:
     virtual int x() const = 0;
     virtual int y() const = 0;
     virtual int width() const = 0;
     virtual int height() const = 0;
     virtual IntSize size() const = 0;
     virtual IntPoint location() const = 0;
 
-    virtual ScrollView* parent() const = 0;
-    virtual ScrollView* root() const = 0;
+    virtual Widget* parent() const = 0;
+    virtual Widget* root() const = 0;
 
     virtual void setFrameRect(const IntRect&) = 0;
     virtual IntRect frameRect() const = 0;
 
     virtual void invalidate() = 0;
     virtual void invalidateRect(const IntRect&) = 0;
 
     virtual ScrollbarOverlayStyle scrollbarOverlayStyle() const = 0;
     virtual void getTickmarks(Vector<IntRect>&) const = 0;
     virtual bool isScrollableAreaActive() const = 0;
@@ skipping 25 matching lines @@
     virtual bool isAlphaLocked() const = 0;
     virtual void setIsAlphaLocked(bool) = 0;
 
 protected:
     virtual ~ScrollbarThemeClient() { }
 };
 
 } // namespace WebCore
 
 #endif // ScollbarThemeClient_h