Split out String, URI and CustomIdent from CSSPrimitiveValue

Source/core/css/CSSStringValueBase.cpp

Index: Source/core/css/CSSStringValueBase.cpp
diff --git a/Source/core/css/CSSStringValueBase.cpp b/Source/core/css/CSSStringValueBase.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..473b0b49857f8a807a5859fb18c1aab6db9444b5
--- /dev/null
+++ b/Source/core/css/CSSStringValueBase.cpp
@@ -0,0 +1,28 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/css/CSSStringValueBase.h"
+
+#include "core/css/CSSMarkup.h"
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+
+template<> String CSSStringValueBase<CSSValue::StringClass>::customCSSText() const
+{
+    return serializeString(m_string);
+}
+
+template<> String CSSStringValueBase<CSSValue::CustomIdentClass>::customCSSText() const
+{
+    return quoteCSSStringIfNeeded(m_string);
+}
+
+template<> String CSSStringValueBase<CSSValue::URIClass>::customCSSText() const
+{
+    return "url(" + quoteCSSURLIfNeeded(m_string) + ")";
+}
+
+} // namespace blink