06/09/2019: Firefox updated to 69.0
I thought Firefox 69.0 would not be possible on KISS due to the new unconditional dependency on dbus. I have written a patch which removes this dependency and allows us to build it again!
Firefox 69.0 introduces something called audio_thread_priority and from what I understand it's a way to prioritize audio threads when needed. This entire "feature" works using dbus to do IPC on Linux and subsequently breaks the --disable-dbus configure flag.
The patch I have written disables audio_thread_priority and in turn causes audio to work the same as it did in 68.0 and below.
Sources: