User Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0
Steps to reproduce:
Option for configuring if Firefox should be build with X11 support or not.
with-X11 -> build same as actual
without-X11 -> being able build and run Firefox completly without X11 server and his libraries
This option would be useful for systems where Wayland is available as only option and are limited by resources (RAM and storage) + head-less machines.
Since support for Wayland slowly maturing, I think this option is relevant.