Tin Can is currently an experimental project. The login is currently using personatest, which is running an older version. I'm not too sure what the status is (I'm a friend of the author) right now with integrating this into persona.
[1] https://bugzilla.mozilla.org/show_bug.cgi?id=878941 [2] https://tools.ietf.org/html/draft-ietf-rtcweb-security-arch-...