jnbek [1] filed a deletion request for firefox-dev [2]:
This package has been a hostile attempt at taking control of the
formerly my firefox-developer PKGBUILD, which is built by strict
standards for Mozilla software. This PKGBUILD autoupdates willy nilly
without any hands on checks to ensure everything went well.
[1] https://aur.archlinux.org/account/jnbek/
[2] https://aur.archlinux.org/pkgbase/firefox-dev/