[Typed OM] Add an "UnsupportedStyleValue" in C++ that just has a string for unknown types

third_party/WebKit/Source/core/css/cssom/CSSUnsupportedStyleValue.h

Index: third_party/WebKit/Source/core/css/cssom/CSSUnsupportedStyleValue.h
diff --git a/third_party/WebKit/Source/core/css/cssom/CSSUnsupportedStyleValue.h b/third_party/WebKit/Source/core/css/cssom/CSSUnsupportedStyleValue.h
new file mode 100644
index 0000000000000000000000000000000000000000..520c0960d6532d508aaaa457409607f8d4eb8861
--- /dev/null
+++ b/third_party/WebKit/Source/core/css/cssom/CSSUnsupportedStyleValue.h
@@ -0,0 +1,34 @@
+// Copyright 2016 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.
+
+#ifndef CSSUnsupportedStyleValue_h
+#define CSSUnsupportedStyleValue_h
+
+#include "core/css/cssom/CSSStyleValue.h"
+
+namespace blink {
+
+class CORE_EXPORT CSSUnsupportedStyleValue final : public CSSStyleValue {
+    WTF_MAKE_NONCOPYABLE(CSSUnsupportedStyleValue);
+public:
+    static CSSUnsupportedStyleValue* create(const String& cssText)
+    {
+        return new CSSUnsupportedStyleValue(cssText);
+    }
+
+    StyleValueType type() const override { return StyleValueType::Unknown; }
+    CSSValue* toCSSValue() const override;
+    CSSValue* toCSSValueWithProperty(CSSPropertyID) const override;
+    String cssString() const override { return m_cssText; }
+
+private:
+    CSSUnsupportedStyleValue(const String& cssText)
+        : m_cssText(cssText) {}
+
+    String m_cssText;
+};
+
+} // namespace blink
+
+#endif // CSSUnsupportedStyleValue_h