Keep the selection of the text field when changed by JS.

Source/core/page/EventHandler.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 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:
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 170 matching lines @@
 
     void focusDocumentView();
 
     void capsLockStateMayHaveChanged(); // Only called by FrameSelection
 
     bool handleTouchEvent(const PlatformTouchEvent&);
 
     bool useHandCursor(Node*, bool isOverLink);
 
     void notifyElementActivated();
+    void notifySelectionChanged();
 
     PassRefPtr<UserGestureToken> takeLastMouseDownGestureToken() { return m_lastMouseDownUserGestureToken.release(); }
 
     int clickCount() { return m_clickCount; }
     bool mouseDownWasSingleClickInSelection() { return m_mouseDownWasSingleClickInSelection; }
 
 private:
     static DragState& dragState();
 
     PassRefPtrWillBeRawPtr<DataTransfer> createDraggingDataTransfer() const;
@@ skipping 212 matching lines @@
     // scroll sequence in this frame, or any child frames. Only used
     // with ScrollCustomization. If some delta has been consumed, a
     // scroll which shouldn't propagate can't cause any element to
     // scroll other than the |m_previousGestureScrolledNode|.
     bool m_deltaConsumedForScrollSequence;
 };
 
 } // namespace blink
 
 #endif // EventHandler_h