clutter-actor: Clip the current draw framebuffer
clutter_actor_set_clip*
was being ignored for actors inside offscreen'd
actors because offscreening uses a different framebuffer.
Let's use the current draw framebuffer (which is always right) instead of assuming the current draw framebuffer is that of the stage. Same as we did in b8340f13.
Closes: gnome-shell#1078 (closed)
Edited by Daniel van Vugt