Playbook: Fix rendering when thumbnailed/minimized

On Playbook, rendering should happen when the application is thumbnailed,
therefore we need to send a window activated event to resume rendering once
the thumbnail is restored from the minimized state.

Change-Id: I0fa5da483dc101e25f718e52859a66edfe5c66c7
Reviewed-by: Bernd Weimer <bweimer@blackberry.com>
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Reviewed-by: Nicolas Arnaud-Cormos <nicolas@kdab.com>
BB10: Do not send deactivate event twice

On BB10, NAVIGATOR_WINDOW_INACTIVE is called before
NAVIGATOR_WINDOW_INVISIBLE, already triggering handleWindowGroupDeactivated()

Change-Id: I7d82c0220fe8dc8e87bfa2b31af6085c7d1d6cee
Reviewed-by: Kevin Krammer <kevin.krammer@kdab.com>
Reviewed-by: Bernd Weimer <bweimer@blackberry.com>
Reviewed-by: Nicolas Arnaud-Cormos <nicolas@kdab.com>