Fix `ReferenceError: event is not defined` error by making sure event param is passed to event cb's
Fix `ReferenceError: event is not defined` error by making sure event param is passed to event cb's

`ReferenceError: event is not defined` error given by Firefox 39.

zlot/Valiant360,flimshaw/Valiant360,zlot/Valiant360,flimshaw/Valiant360