fix(transition): not checking for event object lead to TypeError

This PR fixes a regression of #698 where it was not covered that the completemethod could have been called outside of an event, thus the event object was not available and accessing it lead into a TypeError

Closes #745

src/definitions/modules/transition.js

@@ -215,7 +215,7 @@ $.fn.transition = function() {
         },
 
         complete: function (event) {
-          if(event.target === element) {
+          if(event && event.target === element) {
               event.stopPropagation();
           }
           module.debug('Animation complete', settings.animation);