WebUI: Undo some usages of ES6 features that break uglify.

chrome/browser/resources/settings/people_page/sync_page.js

 // Copyright 2015 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.
 
 (function() {
 
 /**
  * Names of the radio buttons which allow the user to choose their encryption
  * mechanism.
  * @enum {string}
@@ skipping 220 matching lines @@
    * Handler for when the sync all data types checkbox is changed.
    * @param {!Event} event
    * @private
    */
   onSyncAllDataTypesChanged_: function(event) {
     if (event.target.checked) {
       this.set('syncPrefs.syncAllDataTypes', true);
 
       // Cache the previously selected preference before checking every box.
       this.cachedSyncPrefs_ = {};
-      for (var dataType of SyncPrefsIndividualDataTypes) {
+      for (var i = 0; i < SyncPrefsIndividualDataTypes.length; i++) {
+        var dataType = SyncPrefsIndividualDataTypes[i];
         // These are all booleans, so this shallow copy is sufficient.
         this.cachedSyncPrefs_[dataType] = this.syncPrefs[dataType];
 
         this.set(['syncPrefs', dataType], true);
       }
     } else if (this.cachedSyncPrefs_) {
       // Restore the previously selected preference.
-      for (dataType of SyncPrefsIndividualDataTypes) {
+      for (var i = 0; i < SyncPrefsIndividualDataTypes.length; i++) {
+        var dataType = SyncPrefsIndividualDataTypes[i];
         this.set(['syncPrefs', dataType], this.cachedSyncPrefs_[dataType]);
       }
     }
 
     this.onSingleSyncDataTypeChanged_();
   },
 
   /**
    * Handler for when any sync data type checkbox is changed (except autofill).
    * @private
@@ skipping 167 matching lines @@
   onLearnMoreTap_: function(event) {
     if (event.target.tagName == 'A') {
       // Stop the propagation of events, so that clicking on links inside
       // checkboxes or radio buttons won't change the value.
       event.stopPropagation();
     }
   }
 });
 
 })();