Launch "safe" Firefox

Launch "safe" Firefox

I'm trying to run jasmine unit tests on a CI server. To do that I have to
launch a browser (FF in my case.)
I have a vnc server running on the server, so the browser has a display to
attach to. However, when the browser is killed or terminated ungracefully
(which can happen if a build fails), If I simply run "/usr/bin/firefox", I
get a pop-up message from Firefox, and obviously the tests won't work.
Is there a set of flag I can use to always launch FF (as if it was a
regular startup ?)
Note that :
/usr/bin/firefox -safe would not work, as it opens a popup to warn about
safe mode
/usr/bin/firefox -P xyz would not work, as it opens a popup to define the
profile
Thanks