Implement ReadableStream as a V8 extra

Source/core/streams/ScriptReadableStreamController.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 ScriptReadableStreamController_h
+#define ScriptReadableStreamController_h
+
+#include "bindings/core/v8/ScriptValue.h"
+#include <v8.h>
+
+namespace blink {
+
+class ScriptReadableStreamController {
+public:
+    explicit ScriptReadableStreamController(ScriptValue stream);
+    void close();
+    double desiredSize() const;
+
+    template<typename ChunkType>
+    void enqueue(ChunkType) const;
+
+    template<typename ErrorType>
+    void error(ErrorType);
+
+private:
+    ScriptValue m_stream;
+};
+
+} // namespace blink
+
+#endif // ScriptReadableStreamController_h