FIXED: changed 'event' to 'domevent'

`$type()` would have returned 'event' but `typeOf()` will return 'domevent'.

http://mootools.net/docs/core/Core/Core#Core:typeOf

and

https://github.com/mootools/mootools-core/wiki/Upgrade-from-1.2-to-1.3-or-1.4 at "Events"