User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Firefox/52.0 Build ID: 20170323110425 Steps to reproduce: I recently changed my password at work to include unicode characters. After doing so, I noticed sites requiring Basic Auth would no longer accept my username and password. A little digging revealed that [Firefox apparently sends only the most significant byte of UTF-8 characters](http://stackoverflow.com/a/9056877/70170), or by my estimation some other single-byte encoding. And while I acknowledge there's probably not a reliable standard for encoding passwords (or usernames for that matter), Chrome does seem to transmit the complete password in UTF-8 and for the systems I was using, that was sufficient to pass the auth check. Actual results: For the password "хорошую работу", Firefox sends "E>@>HCN @01>BC" (0x45, 0x3e, 0x40, 0x3e, 0x48, 0x43, 0x4e, 0x20, 0x40, 0x30, 0x31, 0x3e, 0x42, 0x43). Expected results: Firefox should send the text UTF-8 encoded, matching the de-facto standard (0xd1, 0x85, 0xd0, 0xbe, 0xd1, 0x80, 0xd0, 0xbe, 0xd1, 0x88, 0xd1, 0x83, 0xd1, 0x8e, 0x20, 0xd1, 0x80, 0xd0, 0xb0, 0xd0, 0xb1, 0xd0, 0xbe, 0xd1, 0x82, 0xd1, 0x83).