optimizing layout performance when only transform3d matrix changed by

Source/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ skipping 95 matching lines @@
     IntSize layoutSize(IncludeScrollbarsInRect = ExcludeScrollbars) const;
     void setLayoutSize(const IntSize&);
 
     // If this is set to false, the layout size will need to be explicitly set by the owner.
     // E.g. WebViewImpl sets its mainFrame's layout size manually
     void setLayoutSizeFixedToFrameSize(bool isFixed) { m_layoutSizeFixedToFrameSize = isFixed; }
     bool layoutSizeFixedToFrameSize() { return m_layoutSizeFixedToFrameSize; }
 
     bool needsFullRepaint() const { return m_doFullRepaint; }
 
-    void updateCompositingLayersAfterStyleChange();
+    void updateCompositingLayersAfterStyleChange(bool fast = false);
     void updateCompositingLayersAfterLayout();
 
     bool hasCompositedContent() const;
     bool isEnclosedInCompositingLayer() const;
 
     void resetScrollbars();
     void prepareForDetach();
     void detachCustomScrollbars();
     virtual void recalculateScrollbarOverlayStyle();
 
@@ skipping 427 matching lines @@
         m_view->setCanRepaintDuringPerformLayout(m_originalValue);
     }
 private:
     FrameView* m_view;
     bool m_originalValue;
 };
 
 } // namespace WebCore
 
 #endif // FrameView_h