Support for CSSOM CSSNamespaceRule interface

Source/core/css/CSSNamespaceRule.h

+// 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.
+
+
+#ifndef CSSNamespaceRule_h
+#define CSSNamespaceRule_h
+
+#include "core/css/CSSRule.h"
+
+namespace blink {
+
+class StyleRuleNamespace;
+
+class CSSNamespaceRule final : public CSSRule {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    static PassRefPtrWillBeRawPtr<CSSNamespaceRule> create(StyleRuleNamespace* rule, CSSStyleSheet* sheet)
+    {
+        return adoptRefWillBeNoop(new CSSNamespaceRule(rule, sheet));
+    }
+
+    ~CSSNamespaceRule() override;
+
+    String cssText() const override;
+    void reattach(StyleRuleBase*) override { }
+
+    AtomicString namespaceURI() const;
+    AtomicString prefix() const;
+
+    DECLARE_VIRTUAL_TRACE();
+
+private:
+    CSSNamespaceRule(StyleRuleNamespace*, CSSStyleSheet*);
+
+    CSSRule::Type type() const override { return NAMESPACE_RULE; }
+
+    RefPtrWillBeMember<StyleRuleNamespace> m_namespaceRule;
+};
+
+DEFINE_CSS_RULE_TYPE_CASTS(CSSNamespaceRule, NAMESPACE_RULE);
+
+} // namespace blink
+
+#endif // CSSNamespaceRule_h