Add "mark promise as handled" change to pipeThrough()

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 _reader = v8.createPrivateSymbol('[[reader]]');
   const _storedError = v8.createPrivateSymbol('[[storedError]]');
   const _controller = v8.createPrivateSymbol('[[controller]]');
@@ skipping 159 matching lines @@
       }
 
       if (mode === undefined) {
         return AcquireReadableStreamDefaultReader(this);
       }
 
       throw new RangeError(errGetReaderBadMode);
     }
 
     pipeThrough({writable, readable}, options) {
-      this.pipeTo(writable, options);
+      const promise = this.pipeTo(writable, options);
+      if (v8.isPromise(promise)) {
+        v8.markPromiseAsHandled(promise);
+      }
       return readable;
     }
 
     pipeTo(dest, {preventClose, preventAbort, preventCancel} = {}) {
       if (!IsReadableStream(this)) {
         return Promise_reject(new TypeError(streamErrors.illegalInvocation));
       }
 
       if (!binding.IsWritableStream(dest)) {
         // TODO(ricea): Think about having a better error message.
@@ skipping 920 matching lines @@
   binding.ReadableStreamDefaultControllerGetDesiredSize = ReadableStreamDefaultControllerGetDesiredSize;
   binding.ReadableStreamDefaultControllerEnqueue = ReadableStreamDefaultControllerEnqueue;
   binding.ReadableStreamDefaultControllerError = ReadableStreamDefaultControllerError;
 
   binding.createReadableStreamWithExternalController =
       (underlyingSource, strategy) => {
         return new ReadableStream(
             underlyingSource, strategy, createWithExternalControllerSentinel);
       };
 });