Use AtomicString instead of StringImpl* in PropertyHandle

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

Index: third_party/WebKit/Source/core/animation/PropertyHandle.cpp
diff --git a/third_party/WebKit/Source/core/animation/PropertyHandle.cpp b/third_party/WebKit/Source/core/animation/PropertyHandle.cpp
index 90b91f19d26399549ad066cef28c6640fc4e4e76..12c144e10e6afe9a51d50fbcb66cbbb26b835c13 100644
--- a/third_party/WebKit/Source/core/animation/PropertyHandle.cpp
+++ b/third_party/WebKit/Source/core/animation/PropertyHandle.cpp
@@ -4,6 +4,8 @@
 
 #include "core/animation/PropertyHandle.h"
 
+#include "wtf/text/AtomicStringHash.h"
+
 namespace blink {
 
 bool PropertyHandle::operator==(const PropertyHandle& other) const {
@@ -28,7 +30,7 @@ unsigned PropertyHandle::hash() const {
     case HandleCSSProperty:
       return m_cssProperty;
     case HandleCSSCustomProperty:
-      return m_propertyName->existingHash();
+      return AtomicStringHash::hash(m_propertyName);
     case HandlePresentationAttribute:
       return -m_cssProperty;
     case HandleSVGAttribute: