widget: limit emission of state-changed:showing
widget: limit emission of state-changed:showing

Sending atspi events notyfying about visibility change during
widget destruction is pointless.

rvandegrift/elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary,rvandegrift/elementary,tasn/elementary,tasn/elementary