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

Source/core/platform/animation/CSSAnimationData.cpp

Index: Source/core/platform/animation/CSSAnimationData.cpp
diff --git a/Source/core/platform/animation/CSSAnimationData.cpp b/Source/core/platform/animation/CSSAnimationData.cpp
index a3bee6aca2a4a66a4a1b0856a70c1f1fd3a2d4b1..277944ba1d3c2c93dc2abe9fe2c91159a52c5ffd 100644
--- a/Source/core/platform/animation/CSSAnimationData.cpp
+++ b/Source/core/platform/animation/CSSAnimationData.cpp
@@ -119,9 +119,9 @@ bool CSSAnimationData::animationsMatchForStyleRecalc(const CSSAnimationData* o)
         && 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;
 }