Firefox -current: hangouts screen sharing cause pledge(2) to kill the browser

Hi ports@

I switched to firefox recently, because with chromium, hangouts screen sharing
doesn't work at all and I need it for work.

While testing Firefox screen sharing in hangouts, pledge kills it with:

"/bsd: firefox[43476]: pledge "", syscall 289"

The syscall itself is shmget(2). Running hangouts with pledge disabled in firefox
works fine (I can share the screen without problems).

I tried to see how to solve the situation without disabling pledge. I modified the
kernel to include shmget(2), shmat(2), shmctl(2) and shmdt(2) in the stdio set
and now, screen sharing works.

Regards.

Andrea