Fix background texture corruption when resuming from suspend on Nvidia
Closes: gnome-shell#1084 (closed)
Note: The only goal of this branch is to fix the background wallpaper (https://bugs.launchpad.net/bugs/1809407) for Xorg sessions. Any other related fixes that don't easily fit into this branch should be proposed and discussed separately. That includes the native backend.
Edited by Daniel van Vugt