Store [-webkit-]transform-origin as a TransformOrigin.

Source/core/css/resolver/StyleBuilderConverter.cpp

Index: Source/core/css/resolver/StyleBuilderConverter.cpp
diff --git a/Source/core/css/resolver/StyleBuilderConverter.cpp b/Source/core/css/resolver/StyleBuilderConverter.cpp
index a4948917ee70b37d9ed618e2e837554aa7b45cc4..565e9bc826b13404bd100a6512fb2d386d9a4191 100644
--- a/Source/core/css/resolver/StyleBuilderConverter.cpp
+++ b/Source/core/css/resolver/StyleBuilderConverter.cpp
@@ -791,4 +791,20 @@ float StyleBuilderConverter::convertTextStrokeWidth(StyleResolverState& state, C
     return primitiveValue->computeLength<float>(state.cssToLengthConversionData());
 }
 
+TransformOrigin StyleBuilderConverter::convertTransformOrigin(StyleResolverState& state, CSSValue* value)
+{
+    CSSValueList* list = toCSSValueList(value);
+    ASSERT(list->length() == 3);
+
+    CSSPrimitiveValue* primitiveValueX = toCSSPrimitiveValue(list->item(0));
+    CSSPrimitiveValue* primitiveValueY = toCSSPrimitiveValue(list->item(1));
+    CSSPrimitiveValue* primitiveValueZ = toCSSPrimitiveValue(list->item(2));
+
+    return TransformOrigin(
+        convertOriginLength<CSSValueLeft, CSSValueRight>(state, primitiveValueX),
+        convertOriginLength<CSSValueTop, CSSValueBottom>(state, primitiveValueY),
+        StyleBuilderConverter::convertComputedLength<float>(state, primitiveValueZ)
+    );
+}
+
 } // namespace blink