ecore: make sure that events are being forwarded first.

ecore: make sure that events are being forwarded first.

In case the model being set has already gotten some event callback
set on it, to avoid strange behavior, like event not propagating,
it seems best to make sure the event are forwarded first.

Reviewed-by: Marcel Hollerbach <marcel-hollerbach@t-online.de>
Differential Revision: https://phab.enlightenment.org/D7483