Streams Implementation Update: async read

Source/core/streams/ReadableStreamReader.idl

 // 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.
 
-enum ReadableStreamState {
-    "readable",
-    "waiting",
-    "closed",
-    "errored"
-};
-
 [
     RuntimeEnabled=ExperimentalStream,
     GarbageCollected,
     ActiveDOMObject,
     Exposed=(Window,Worker),
 ] interface ReadableStreamReader {
     // FIXME: Add constructor.
 
     [CallWith=ScriptState] readonly attribute Promise closed;
-    readonly attribute boolean isActive;
-    [CallWith=ScriptState] readonly attribute Promise ready;
-    readonly attribute ReadableStreamState state;
+    [CallWith=ScriptState] Promise read();
 
     [CallWith=ScriptState] Promise cancel(any reason);
-    [CallWith=ScriptState, RaisesException] any read();
-    void releaseLock();
+    [RaisesException] void releaseLock();
 };