gdk: stage: do not ensure native windows are created with foreign windows
gdk: stage: do not ensure native windows are created with foreign windows

For foreign windows this should be dealt with by the embedding
framework. In particular on Wayland with foreign windows, we might
want to create a subsurface and use the foreign window only for events
and frame clock synchronization.

https://bugzilla.gnome.org/show_bug.cgi?id=754697

Distrotech/clutter,jigpu/clutter,jigpu/clutter,GNOME/clutter,Distrotech/clutter,Distrotech/clutter,jigpu/clutter,jigpu/clutter,Distrotech/clutter,jigpu/clutter,GNOME/clutter,GNOME/clutter,Distrotech/clutter,jigpu/clutter,GNOME/clutter,GNOME/clutter,Distrotech/clutter