Reject port 80 non-onion destinations

[JeremyRand]

We should add an option (per eTLD) to reject destinations that are not .onion domains if they are using TCP port 80. This has the effect of guaranteeing that the eTLD will use a secure origin for HTTP traffic.

[JeremyRand]

Maybe wait on this until Namecoin TLS support for Tor Browser is further along?

[yanmaani]

Seems a bit gross. If it's needed, it's needed, but it seems conceptually cleaner to limit ourselves to .onion and punt on this until later.

[JeremyRand]

Seems low priority at the moment, but if a volunteer wants to implement this, I'd accept a PR.