Clear undo stack when text control is set programatically

Source/core/editing/Editor.h

 /*
  * Copyright (C) 2006, 2007, 2008 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 150 matching lines @@
     bool insertLineBreak();
     bool insertParagraphSeparator();
 
     bool isOverwriteModeEnabled() const { return m_overwriteModeEnabled; }
     void toggleOverwriteModeEnabled();
 
     bool canUndo();
     void undo();
     bool canRedo();
     void redo();
+    void clearUndoStack();
 
     void setBaseWritingDirection(WritingDirection);
 
     // smartInsertDeleteEnabled and selectTrailingWhitespaceEnabled are
     // mutually exclusive, meaning that enabling one will disable the other.
     bool smartInsertDeleteEnabled() const;
     bool isSelectTrailingWhitespaceEnabled() const;
 
     bool preventRevealSelection() const { return m_preventRevealSelection; }
 
@@ skipping 108 matching lines @@
 
 inline bool Editor::markedTextMatchesAreHighlighted() const
 {
     return m_areMarkedTextMatchesHighlighted;
 }
 
 
 } // namespace WebCore
 
 #endif // Editor_h