Add outline files for StylePropertyMap.

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

+// 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 ImmutableStylePropertyMap_h
+#define ImmutableStylePropertyMap_h
+
+#include "core/css/cssom/StylePropertyMap.h"
+
+namespace blink {
+
+class CORE_EXPORT ImmutableStylePropertyMap : public StylePropertyMap {
+    WTF_MAKE_NONCOPYABLE(ImmutableStylePropertyMap);
+public:
+    void set(CSSPropertyID, StyleValueOrStyleValueSequenceOrString&, ExceptionState& exceptionState) override
+    {
+        exceptionState.throwTypeError("This StylePropertyMap is immutable.");
+    }
+
+    void append(CSSPropertyID, StyleValueOrStyleValueSequenceOrString&, ExceptionState& exceptionState) override
+    {
+        exceptionState.throwTypeError("This StylePropertyMap is immutable.");
+    }
+
+    void remove(CSSPropertyID, ExceptionState& exceptionState) override
+    {
+        exceptionState.throwTypeError("This StylePropertyMap is immutable.");
+    }
+};
+
+} // namespace blink
+
+#endif