Use AtomicString instead of StringImpl* in PropertyHandle

third_party/WebKit/Source/core/animation/PropertyHandle.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/animation/PropertyHandle.h"
 
+#include "wtf/text/AtomicStringHash.h"
+
 namespace blink {
 
 bool PropertyHandle::operator==(const PropertyHandle& other) const {
   if (m_handleType != other.m_handleType)
     return false;
 
   switch (m_handleType) {
     case HandleCSSProperty:
     case HandlePresentationAttribute:
       return m_cssProperty == other.m_cssProperty;
     case HandleCSSCustomProperty:
       return m_propertyName == other.m_propertyName;
     case HandleSVGAttribute:
       return m_svgAttribute == other.m_svgAttribute;
     default:
       return true;
   }
 }
 
 unsigned PropertyHandle::hash() const {
   switch (m_handleType) {
     case HandleCSSProperty:
       return m_cssProperty;
     case HandleCSSCustomProperty:
-      return m_propertyName->existingHash();
+      return AtomicStringHash::hash(m_propertyName);
     case HandlePresentationAttribute:
       return -m_cssProperty;
     case HandleSVGAttribute:
       return QualifiedNameHash::hash(*m_svgAttribute);
     default:
       NOTREACHED();
       return 0;
   }
 }
 
 }  // namespace blink