In short, if GTK+ supports X11, we should too. If it supports Wayland, we should too. Support for the specific system is observable through the gtk+-(x11|wayland|etc.)-3.0.pc files.
I like this plan!
Created attachment 235902 [details]
Comment on attachment 235902 [details]
Clearing flags on attachment: 235902
Committed r171988: <http://trac.webkit.org/changeset/171988>
All reviewed patches have been landed. Closing bug.