CSSValue Immediates: Replace CSSPrimitiveValue usage with const references

Source/core/css/CSSCrossfadeValue.h

Index: Source/core/css/CSSCrossfadeValue.h
diff --git a/Source/core/css/CSSCrossfadeValue.h b/Source/core/css/CSSCrossfadeValue.h
index d92841794edb62c36f8e880c2e6fbe9eda194909..ff8cd9bad1a0f271e43d38dfeae05799ecb873cf 100644
--- a/Source/core/css/CSSCrossfadeValue.h
+++ b/Source/core/css/CSSCrossfadeValue.h
@@ -42,7 +42,7 @@ class LayoutObject;
 class CSSCrossfadeValue final : public CSSImageGeneratorValue {
     friend class CrossfadeSubimageObserverProxy;
 public:
-    static PassRefPtrWillBeRawPtr<CSSCrossfadeValue> create(CSSValue fromValue, CSSValue toValue)
+    static PassRefPtrWillBeRawPtr<CSSCrossfadeValue> create(const CSSValue& fromValue, const CSSValue& toValue)
     {
         return adoptRefWillBeNoop(new CSSCrossfadeValue(fromValue, toValue));
     }
@@ -60,7 +60,7 @@ public:
 
     void loadSubimages(Document*);
 
-    void setPercentage(CSSPrimitiveValue percentageValue) { m_percentageValue = percentageValue; }
+    void setPercentage(const CSSPrimitiveValue& percentageValue) { m_percentageValue = percentageValue; }
 
     bool hasFailedOrCanceledSubresources() const;
 
@@ -74,7 +74,7 @@ public:
     DECLARE_TRACE_AFTER_DISPATCH();
 
 private:
-    CSSCrossfadeValue(CSSValue fromValue, CSSValue toValue)
+    CSSCrossfadeValue(const CSSValue& fromValue, const CSSValue& toValue)
         : CSSImageGeneratorValue(CrossfadeClass)
         , m_fromValue(fromValue)
         , m_toValue(toValue)