MD Settings: Eliminate use of ES6 for Chrome OS

chrome/browser/resources/settings/bluetooth_page/bluetooth_device_dialog.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.
 
 cr.exportPath('settings');
 
 (function() {
 
 var PairingEventType = chrome.bluetoothPrivate.PairingEventType;
 
@@ skipping 42 matching lines @@
       this.close();
   },
 
   /** @private */
   deviceListChanged_: function() {
     this.updateScrollableContents();
     if (this.itemWasFocused_ || !this.getUnpaired_().length)
       return;
     // If the iron-list is populated with at least one visible item then
     // focus it.
-    let item = this.$$('iron-list bluetooth-device-list-item');
+    var item = this.$$('iron-list bluetooth-device-list-item');
     if (item && item.offsetParent != null) {
       item.focus();
       this.itemWasFocused_ = true;
       return;
     }
     // Otherwise try again.
     setTimeout(function() { this.deviceListChanged_(); }.bind(this), 100);
   },
 
   /** @private */
@@ skipping 332 matching lines @@
   },
 
   /** @private */
   onDialogCanceled_: function() {
     if (this.dialogId == 'pairDevice')
       this.sendResponse_(chrome.bluetoothPrivate.PairingResponse.CANCEL);
   },
 });
 
 })();