Prevent CSS class listing from failing for elements with no CSS classes (fixes #473)

Author: fblundun

src/js/lib/helpers.js

@@ -163,7 +163,7 @@
 	 * List the classes of a DOM element without using elt.classList (for compatibility with IE 9)
 	 */
 	object.getCssClasses = function (elt) {
-		return elt.className.match(/\S+/g);
+		return elt.className.match(/\S+/g) || [];
 	};
 
 	/*