Introduce CSS_VALUE_TYPE_CASTS macro to cast CSSValue

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 219 matching lines @@
     }
     return true;
 }
 
 template<typename CSSValueType>
 inline bool compareCSSValuePtr(const RefPtr<CSSValueType>& first, const RefPtr<CSSValueType>& second)
 {
     return first ? second && first->equals(*second) : !second;
 }
 
+#define DEFINE_CSS_VALUE_TYPE_CASTS(ValueTypeName) \
+inline const CSS##ValueTypeName* toCSS##ValueTypeName(const CSSValue* value) \
+{ \
+    ASSERT_WITH_SECURITY_IMPLICATION(!value || value->is##ValueTypeName()); \
+    return static_cast<const CSS##ValueTypeName*>(value); \
+} \
+inline CSS##ValueTypeName* toCSS##ValueTypeName(CSSValue* value) \
+{ \
+    ASSERT_WITH_SECURITY_IMPLICATION(!value || value->is##ValueTypeName()); \
+    return static_cast<CSS##ValueTypeName*>(value); \
+} \
+void toCSS##ValueTypeName(const CSS##ValueTypeName*); \
+void toCSS##ValueTypeName(const CSS##ValueTypeName&)
+
 } // namespace WebCore
 
 #endif // CSSValue_h