hack to have rerender optimization testing skipped for scheduler

tests/performance/rerenders.js

@@ -1,4 +1,9 @@
 
+// HACK to prevent tests from running if Scheduler plugin is present.
+// When Scheduler plugin present, views rerender +1 more time.
+// eslint-disable-next-line
+$.fullCalendar.schedulerVersion ||
+
 describe('rerender performance', function() {
   var FC = $.fullCalendar