CSSValue Immediates: Make toCSSPrimitiveValue() return a const reference

Source/core/css/CSSValue.h

Index: Source/core/css/CSSValue.h
diff --git a/Source/core/css/CSSValue.h b/Source/core/css/CSSValue.h
index b2f0a4ef382f1e1c301ec9e2f4a9503e59ef061c..b9d3b052e55182e2427b6a6f048856802d2d3724 100644
--- a/Source/core/css/CSSValue.h
+++ b/Source/core/css/CSSValue.h
@@ -72,7 +72,7 @@ public:
     }
 
     // Implicit conversion from CSSPrimitiveValue.
-    CSSValue(CSSPrimitiveValue cssPrimitiveValue)
+    CSSValue(const CSSPrimitiveValue& cssPrimitiveValue)
         : m_data(static_cast<CSSValueObject*>(cssPrimitiveValue.get()))
     {
         ref();
@@ -253,7 +253,7 @@ public:
     }
 
     // Implicit conversion from CSSPrimitiveValue.
-    NullableCSSValue(CSSPrimitiveValue cssPrimitiveValue)
+    NullableCSSValue(const CSSPrimitiveValue& cssPrimitiveValue)
         : m_data(static_cast<CSSValueObject*>(cssPrimitiveValue.get()))
     {
         ref();
@@ -363,6 +363,7 @@ private:
 static_assert(sizeof(CSSValue) == sizeof(void*), "CSSValue should be pointer-sized");
 static_assert(sizeof(NullableCSSValue) == sizeof(void*), "CSSValue should be pointer-sized");
 static_assert(sizeof(CSSValue) == sizeof(NullableCSSValue), "Both CSSValue containers must contain the same data");
+static_assert(sizeof(CSSValue) == sizeof(CSSPrimitiveValue), "Both CSSValue and CSSPrimitiveValue must contain the same data");
 
 template<size_t inlineCapacity>
 inline bool compareCSSValueVector(const WillBeHeapVector<CSSValue, inlineCapacity>& firstVector, const WillBeHeapVector<CSSValue, inlineCapacity>& secondVector)
@@ -397,11 +398,18 @@ inline bool compareCSSValueVector(const WillBeHeapVector<CSSValue, inlineCapacit
     }
 
 // Returns by value on purpose.
-inline CSSPrimitiveValue toCSSPrimitiveValue(const CSSValue& value)
+inline const CSSPrimitiveValue& toCSSPrimitiveValue(const CSSValue& value)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(value.isPrimitiveValue());
-    return CSSPrimitiveValue(static_cast<CSSPrimitiveValue::CSSLargePrimitiveValue*>(value.get()));
+    return *reinterpret_cast<const CSSPrimitiveValue*>(&value);
 }
+/*
+inline CSSPrimitiveValue& toCSSPrimitiveValue(const CSSValue& value)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(value.isPrimitiveValue());
+    return *const_cast<CSSPrimitiveValue*>(reinterpret_cast<const CSSPrimitiveValue*>(&value));
+}
+*/
 
 } // namespace blink