Enabling the devtools.chrome.enabled pref on my Linux debug build made the build rather crashy. (It was crashy in the sense that it crashed on shutdown while quitting with a lot of windows open, and it crashed restoring that same large session, but it wasn't crashy enough that loading a single page would necessarily crash.) I ran into this a little over a week ago and haven't had the chance to investigate further, but I think it might have had something to do with signal handlers in the case where the JIT was relying on SEGV handlers.