Set up clip and scroll parents on the blink side.

Source/core/platform/ScrollableArea.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2008, 2011 Apple 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 138 matching lines @@
 }
 
 void ScrollableArea::notifyScrollPositionChanged(const IntPoint& position)
 {
     scrollPositionChanged(position);
     scrollAnimator()->setCurrentPosition(position);
 }
 
 void ScrollableArea::scrollPositionChanged(const IntPoint& position)
 {
-    TRACE_EVENT0("webkit", "ScrollableArea::scrollPositionChanged");
+    TRACE_EVENT0("webkit,impl-scroll", "ScrollableArea::scrollPositionChanged");
 
     IntPoint oldPosition = scrollPosition();
     // Tell the derived class to scroll its contents.
     setScrollOffset(position);
 
     Scrollbar* verticalScrollbar = this->verticalScrollbar();
 
     // Tell the scrollbars to update their thumb postions.
     if (Scrollbar* horizontalScrollbar = this->horizontalScrollbar()) {
         horizontalScrollbar->offsetDidChange();
@@ skipping 241 matching lines @@
 {
     return scrollSize(orientation);
 }
 
 float ScrollableArea::pixelStep(ScrollbarOrientation) const
 {
     return 1;
 }
 
 } // namespace WebCore