Copy shape region to Deleted
Currently, the shape region is not copied to the Deleted. If either SurfaceItemX11 or SurfaceItemXwayland needs to build quads for a shaped window, it won't be able to do so properly because the corresponding x11 window is long time gone.
If the shape region changes before the window is unmapped, you may still see visual artifacts. Unfortunately, the only way to fix that bug is to switch to wayland.