Freeze break request for mutter!486

[Carlos Garnacho <carlosg gnome org>]

Hi!,

I figured better doing this here than over IRC... In the end several
people agreed at #gnome-shell that
https://gitlab.gnome.org/GNOME/mutter/merge_requests/486 may be a
better fix for the swapped colors regression. Also accounting that
there's been other reported issues around xwayland and drivers without
hw accel.

The MR undoes the revert that was meant to be temporary, and removes
the root of the problem without apparent drawbacks. Sounds good to go?

Cheers,
  Carlos