DOM: Do not skip 'replace data' operation on setting identical string to CharacterData.

third_party/WebKit/Source/core/dom/CharacterData.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2013 Apple Inc. All
  * rights reserved.
  *
  * 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
  * version 2 of the License, or (at your option) any later version.
@@ skipping 24 matching lines @@
 #include "wtf/CheckedNumeric.h"
 
 namespace blink {
 
 void CharacterData::atomize() {
   m_data = AtomicString(m_data);
 }
 
 void CharacterData::setData(const String& data) {
   const String& nonNullData = !data.isNull() ? data : emptyString;
-  if (m_data == nonNullData)
-    return;
-
   unsigned oldLength = length();
 
   setDataAndUpdate(nonNullData, 0, oldLength, nonNullData.length(),
                    UpdateFromNonParser);
   document().didRemoveText(this, 0, oldLength);
 }
 
 String CharacterData::substringData(unsigned offset,
                                     unsigned count,
                                     ExceptionState& exceptionState) {
@@ skipping 164 matching lines @@
     dispatchSubtreeModifiedEvent();
   }
   InspectorInstrumentation::characterDataModified(this);
 }
 
 int CharacterData::maxCharacterOffset() const {
   return static_cast<int>(length());
 }
 
 }  // namespace blink