MD Settings: Convert all usages of .bind(this) to use ES6 arrow function.

chrome/browser/resources/settings/controls/settings_idle_load.js

 // Copyright 2017 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
  * settings-idle-load is a simple variant of dom-if designed for lazy
  * loading and rendering of elements that are accessed imperatively. A URL is
  * given that holds the elements to be loaded lazily.
  */
@@ skipping 29 matching lines @@
   },
 
   /**
    * @return {!Promise<Element>} Child element which has been stamped into the
    *     DOM tree.
    */
   get: function() {
     if (this.loading_)
       return this.loading_;
 
-    this.loading_ = new Promise(function(resolve, reject) {
-      this.importHref(this.url, function() {
+    this.loading_ = new Promise((resolve, reject) => {
+      this.importHref(this.url, () => {
         assert(!this.ctor);
         this.templatize(this);
         assert(this.ctor);
 
         var instance = this.stamp({});
 
         assert(!this.child_);
         this.child_ = instance.root.firstElementChild;
 
         this.parentNode.insertBefore(instance.root, this);
         resolve(this.child_);
 
         this.fire('lazy-loaded');
-      }.bind(this), reject, true);
-    }.bind(this));
+      }, reject, true);
+    });
 
     return this.loading_;
   },
 
   /**
    * @param {string} prop
    * @param {Object} value
    */
   _forwardParentProp: function(prop, value) {
     if (this.child_)
       this.child_._templateInstance[prop] = value;
   },
 
   /**
    * @param {string} path
    * @param {Object} value
    */
   _forwardParentPath: function(path, value) {
     if (this.child_)
       this.child_._templateInstance.notifyPath(path, value, true);
   }
 });