WebUI: Allow rejecting a promise that is returned from cr.sendWithPromise().

ui/webui/resources/js/promise_resolver.js

 // Copyright 2016 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.
 
 /**
  * @fileoverview PromiseResolver is a helper class that allows creating a
  * Promise that will be fulfilled (resolved or rejected) some time later.
  *
  * Example:
  *  var resolver = new PromiseResolver();
  *  resolver.promise.then(function(result) {
  *    console.log('resolved with', result);
  *  });
  *  ...
  *  ...
  *  resolver.resolve({hello: 'world'});
  */
 
-/**
- * @constructor
- */
+/** @constructor */
 function PromiseResolver() {
   /** @type {!Function} */
   this.resolve;
 
   /** @type {!Function} */
   this.reject;
 
   /** @type {!Promise} */
   this.promise = new Promise(function(resolve, reject) {
     this.resolve = resolve;
     this.reject = reject;
   }.bind(this));
 }