Tiling2: Fix handling windows that become untilable after we've added them.
Tiling2: Fix handling windows that become untilable after we've added them.

This fixes T946.

tizenorg/platform.upstream.enlightenment,rvandegrift/e,FlorentRevest/Enlightenment,tasn/enlightenment,rvandegrift/e,tizenorg/platform.upstream.enlightenment,tasn/enlightenment,rvandegrift/e,FlorentRevest/Enlightenment,tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment,tasn/enlightenment