Split out CSSPrimitiveValue's PropertyID into CSSCustomIdentValue

third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.cpp

Index: third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.cpp b/third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.cpp
index de5f8a2f3de2c303d5c596146acfe46f960bab66..6053cc91df5f165ecdb2f8a6e13a5ab34fabe39c 100644
--- a/third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.cpp
@@ -368,12 +368,15 @@ CSSTransitionData::TransitionProperty CSSToStyleMap::mapAnimationProperty(CSSVal
 {
     if (value->isInitialValue())
         return CSSTransitionData::initialProperty();
-    if (value->isCustomIdentValue())
-        return CSSTransitionData::TransitionProperty(toCSSCustomIdentValue(value)->value());
+    if (value->isCustomIdentValue()) {
+        const CSSCustomIdentValue& customIdentValue = toCSSCustomIdentValue(*value);
+        if (customIdentValue.isKnownPropertyID())
+            return CSSTransitionData::TransitionProperty(customIdentValue.valueAsPropertyID());
+        return CSSTransitionData::TransitionProperty(customIdentValue.value());
+    }
     CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(value);
-    if (primitiveValue->getValueID() == CSSValueNone)
-        return CSSTransitionData::TransitionProperty(CSSTransitionData::TransitionNone);
-    return CSSTransitionData::TransitionProperty(primitiveValue->getPropertyID());
+    ASSERT(primitiveValue->getValueID() == CSSValueNone);
+    return CSSTransitionData::TransitionProperty(CSSTransitionData::TransitionNone);
 }
 
 PassRefPtr<TimingFunction> CSSToStyleMap::mapAnimationTimingFunction(CSSValue* value, bool allowStepMiddle)