Add a utility class to call stream methods implemented with v8 extras.

third_party/WebKit/Source/core/streams/ReadableStream.js

 // 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.
 
 (function(global, binding, v8) {
   'use strict';
 
   const readableStreamController = v8.createPrivateSymbol('[[controller]]');
   const readableStreamQueue = v8.createPrivateSymbol('[[queue]]');
   const readableStreamQueueSize =
@@ skipping 743 matching lines @@
     value: ReadableStream,
     enumerable: false,
     configurable: true,
     writable: true
   });
 
   //
   // Exports to Blink
   //
 
+  binding.AcquireReadableStreamReader = AcquireReadableStreamReader;
+  binding.IsReadableStream = IsReadableStream;
   binding.IsReadableStreamDisturbed = IsReadableStreamDisturbed;
+  binding.IsReadableStreamLocked = IsReadableStreamLocked;
+  binding.IsReadableStreamReader = IsReadableStreamReader;
+  binding.ReadFromReadableStreamReader = ReadFromReadableStreamReader;
 });