Follow up to MR41: hide identity-permission-box in urlbar
requested to merge 1peter10/mobile-config-firefox:urlbar-cleanup-follow-up-hide-identity-permission-box into master
This MR is more work on #66 (closed), which with this should be truly solved (for now ;-) ).
It hides a menu that (among maybe other things) has the purpose to allow autoplay - it pops up, e.g., on tagesschau.de - see 
for a visual (it's the wide one between the padlock and reader mode).
I think we can safely hide this without negatively impacting users.