reset VisibleSelection at the Undo command.

Source/core/dom/Node.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 656 matching lines @@
 
     PassRefPtrWillBeRawPtr<NodeList> getDestinationInsertionPoints();
 
     void setAlreadySpellChecked(bool flag) { setFlag(flag, AlreadySpellCheckedFlag); }
     bool isAlreadySpellChecked() { return getFlag(AlreadySpellCheckedFlag); }
 
     bool isFinishedParsingChildren() const { return getFlag(IsFinishedParsingChildrenFlag); }
 
     virtual void trace(Visitor*) OVERRIDE;
 
+    unsigned lengthOfContents() const;
+
 private:
     enum NodeFlags {
         HasRareDataFlag = 1,
 
         // Node type flags. These never change once created.
         IsTextFlag = 1 << 1,
         IsContainerFlag = 1 << 2,
         IsElementFlag = 1 << 3,
         IsHTMLFlag = 1 << 4,
         IsSVGFlag = 1 << 5,
@@ skipping 218 matching lines @@
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showNode(const WebCore::Node*);
 void showTree(const WebCore::Node*);
 void showNodePath(const WebCore::Node*);
 #endif
 
 #endif