fix test for ie11
fix test for ie11

arshaw/fullcalendar,arshaw/fullcalendar,oleg-babintsev/fullcalendar,fullcalendar/fullcalendar,oleg-babintsev/fullcalendar,fullcalendar/fullcalendar,oleg-babintsev/fullcalendar,fullcalendar/fullcalendar,fullcalendar/fullcalendar,arshaw/fullcalendar,arshaw/fullcalendar