Get rid of redundant layout tree update related to selection

third_party/WebKit/Source/core/editing/FrameSelection.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 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:
  * 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 151 matching lines @@
   // Call this after doing user-triggered selections to make it easy to delete
   // the frame you entirely selected.
   void selectFrameElementInParentIfFullySelected();
 
   bool contains(const LayoutPoint&);
 
   SelectionType getSelectionType() const {
     return selection().getSelectionType();
   }
 
-  TextAffinity affinity() const { return selection().affinity(); }
+  TextAffinity affinity() const { return selectionInDOMTree().affinity(); }
 
   bool modify(EAlteration,
               SelectionDirection,
               TextGranularity,
               EUserTriggered = NotUserTriggered);
   enum VerticalDirection { DirectionUp, DirectionDown };
   bool modify(EAlteration, unsigned verticalDistance, VerticalDirection);
 
   // Moves the selection extent based on the selection granularity strategy.
   // This function does not allow the selection to collapse. If the new
@@ skipping 167 matching lines @@
 
 }  // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const blink::FrameSelection&);
 void showTree(const blink::FrameSelection*);
 #endif
 
 #endif  // FrameSelection_h