CSSValue Immediates: Replace CSSPrimitiveValue usage with const references

Source/core/css/CSSValue.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 379 matching lines @@
         return *static_cast<thisType*>(value.get()); \
     } \
     inline thisType* to##thisType(const NullableCSSValue& value) \
     { \
         if (!value) \
             return nullptr; \
         ASSERT_WITH_SECURITY_IMPLICATION(value->predicate); \
         return static_cast<thisType*>(value.get()); \
     }
 
-// Returns by value on purpose.
 inline const CSSPrimitiveValue& toCSSPrimitiveValue(const CSSValue& value)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(value.isPrimitiveValue());
     return *reinterpret_cast<const CSSPrimitiveValue*>(&value);
 }
+inline const CSSPrimitiveValue& toCSSPrimitiveValue(const NullableCSSValue& value)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(value && value->isPrimitiveValue());
+    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
 
 WTF_ALLOW_CLEAR_UNUSED_SLOTS_WITH_MEM_FUNCTIONS(blink::CSSValue);
 WTF_ALLOW_CLEAR_UNUSED_SLOTS_WITH_MEM_FUNCTIONS(blink::NullableCSSValue);
 
 #endif // CSSValue_h