Comment 12 for bug 964584

Also, could you please get a backtrace with debugging symbols installed? You need firefox-dbg, libglib2.0-0-dbg, libdbusmenu-glib4-dbgsym and libdbusmenu-gtk4-dbgsym (instructions for adding the debug symbol repo are https://wiki.ubuntu.com/DebuggingProgramCrash#Debug_Symbol_Packages)

Thanks!