Make PromiseResolver's members read-only

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 @struct
  * @template T
  */
 function PromiseResolver() {
-  /** @type {function(T): void} */
-  this.resolve;
+  /** @private {function(T): void} */
+  this.resolve_;
 
-  /** @type {function(*=): void} */
-  this.reject;
+  /** @private {function(*=): void} */
+  this.reject_;
 
-  /** @type {!Promise<T>} */
-  this.promise = new Promise(function(resolve, reject) {
-    this.resolve = resolve;
-    this.reject = reject;
+  /** @private {!Promise<T>} */
+  this.promise_ = new Promise(function(resolve, reject) {
+    this.resolve_ = resolve;
+    this.reject_ = reject;
   }.bind(this));
 }
+
+PromiseResolver.prototype = {
+  /** @return {!Promise<T>} */
+  get promise() { return this.promise_; },
+  set promise(p) { assertNotReached(); },
+
+  /** @return {function(T): void} */
+  get resolve() { return this.resolve_; },
+  set resolve(r) { assertNotReached(); },
+
+  /** @return {function(*=): void} */
+  get reject() { return this.reject_; },
+  set reject(s) { assertNotReached(); },
+};