Fix ReadableStream getReader({mode: 'byob'})

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 readableStreamReader = v8.createPrivateSymbol('[[reader]]');
   const readableStreamStoredError = v8.createPrivateSymbol('[[storedError]]');
   const readableStreamController = v8.createPrivateSymbol('[[controller]]');
@@ skipping 154 matching lines @@
 
       return ReadableStreamCancel(this, reason);
     }
 
     getReader({ mode } = {}) {
       if (IsReadableStream(this) === false) {
         throw new TypeError(errIllegalInvocation);
       }
 
       if (mode === 'byob') {
-        if (IsReadableByteStreamDefaultController(this[readableStreamController]) === false) {
-          throw new TypeError(errGetReaderNotByteStream);
-        }
-
-        return AcquireReadableStreamBYOBReader(this);
+        // TODO(ricea): When BYOB readers are supported:
+        //
+        // a. If
+        // ! IsReadableByteStreamController(this.[[readableStreamController]])
+        // is false, throw a TypeError exception.
+        // b. Return ? AcquireReadableStreamBYOBReader(this).
+        throw new TypeError(errGetReaderNotByteStream);
       }
 
       if (mode === undefined) {
         return AcquireReadableStreamDefaultReader(this);
       }
 
       throw new RangeError(errGetReaderBadMode);
     }
 
     tee() {
@@ skipping 730 matching lines @@
   binding.ReadableStreamDefaultControllerGetDesiredSize = ReadableStreamDefaultControllerGetDesiredSize;
   binding.ReadableStreamDefaultControllerEnqueue = ReadableStreamDefaultControllerEnqueue;
   binding.ReadableStreamDefaultControllerError = ReadableStreamDefaultControllerError;
 
   binding.createReadableStreamWithExternalController =
       (underlyingSource, strategy) => {
         return new ReadableStream(
             underlyingSource, strategy, createWithExternalControllerSentinel);
       };
 });