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

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

Index: chrome/browser/resources/settings/people_page/sync_page.js
diff --git a/chrome/browser/resources/settings/people_page/sync_page.js b/chrome/browser/resources/settings/people_page/sync_page.js
index 29f89a35c213092e9dab41428b272f3259ff0953..b22155deedc7df16764d3242108968f5a158c68f 100644
--- a/chrome/browser/resources/settings/people_page/sync_page.js
+++ b/chrome/browser/resources/settings/people_page/sync_page.js
@@ -238,7 +238,8 @@ Polymer({
 
       // 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];
 
@@ -246,7 +247,8 @@ Polymer({
       }
     } 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]);
       }
     }