This is a set of patches, scripts and a manifest to build latest Firefox using Flatpak. It is using GNOME 3.22 as base runtime.
Run setup_repo.sh to download GNOME 3.20 SDK and setup a local Flatpak repo.
Now we're ready to run build.sh, which will build Firefox from master branch (using Github's mirror).
After the build is finished you can start sandboxed Firefox:
$ flatpak run org.mozilla.Firefox