| Index: qunit/common.js | 
| diff --git a/qunit/common.js b/qunit/common.js | 
| index 8142b621d4e71d019239b964b1d52bb4fb6943d8..e5ff9bfeb0d071e864299bd888f4f813dd74372a 100644 | 
| --- a/qunit/common.js | 
| +++ b/qunit/common.js | 
| @@ -43,9 +43,9 @@ function restoreFilterComponents() | 
| function preparePrefs() | 
| { | 
| this._pbackup = Object.create(null); | 
| -  for (var pref in Prefs) | 
| +  for (let pref in Prefs) | 
| { | 
| -    var value = Prefs[pref]; | 
| +    let value = Prefs[pref]; | 
| this._pbackup[pref] = value; | 
| } | 
| Prefs.enabled = true; | 
| @@ -53,7 +53,7 @@ function preparePrefs() | 
|  | 
| function restorePrefs() | 
| { | 
| -  for (var pref in this._pbackup) | 
| +  for (let pref in this._pbackup) | 
| Prefs[pref] = this._pbackup[pref]; | 
| } | 
|  | 
|  |