Have CSSAnimationData::name() / initialAnimationName() return an AtomicString

Source/core/platform/animation/CSSAnimationData.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 101 matching lines @@
     return m_name == o->m_name
         && m_playState == o->m_playState
         && m_property == o->m_property
         && m_mode == o->m_mode
         && m_nameSet == o->m_nameSet
         && m_playStateSet == o->m_playStateSet
         && m_propertySet == o->m_propertySet
         && m_isNone == o->m_isNone;
 }
 
-const String& CSSAnimationData::initialAnimationName()
+const AtomicString& CSSAnimationData::initialAnimationName()
 {
-    DEFINE_STATIC_LOCAL(String, initialValue, ("none"));
+    DEFINE_STATIC_LOCAL(const AtomicString, initialValue, ("none"));
     return initialValue;
 }
 
 } // namespace WebCore