CSSValue Immediates: Replace CSSValue usage with const references

Source/core/animation/css/CSSAnimations.cpp

Index: Source/core/animation/css/CSSAnimations.cpp
diff --git a/Source/core/animation/css/CSSAnimations.cpp b/Source/core/animation/css/CSSAnimations.cpp
index 26066096be89917cd4fd9f7f311ab91c4f19f5cd..6129530976eed09b101be461838612c3b2f3e363 100644
--- a/Source/core/animation/css/CSSAnimations.cpp
+++ b/Source/core/animation/css/CSSAnimations.cpp
@@ -89,7 +89,7 @@ static PassRefPtrWillBeRawPtr<StringKeyframeEffectModel> createKeyframeEffectMod
             CSSPropertyID property = properties.propertyAt(j).id();
             specifiedPropertiesForUseCounter.add(property);
             if (property == CSSPropertyAnimationTimingFunction) {
-                CSSValue value = properties.propertyAt(j).value();
+                const CSSValue& value = properties.propertyAt(j).value();
                 RefPtr<TimingFunction> timingFunction;
                 if (value.isInheritedValue() && parentStyle->animations()) {
                     timingFunction = parentStyle->animations()->timingFunctionList()[0];