Disable es3 for tests and customizer.js.

docs/assets/js/src/customizer.js

@@ -6,6 +6,7 @@
  * details, see http://creativecommons.org/licenses/by/3.0/.
  */
 
+/* jshint es3:false */
 /* global JSZip, less, autoprefixer, saveAs, UglifyJS, __configBridge, __js, __less, __fonts */
 
 window.onload = function () { // wait for load in a dumb way because B-0

js/tests/unit/.jshintrc

 {
   "extends" : "../../.jshintrc",
   "devel"   : true,
+  "es3"     : false,
   "qunit"   : true
 }