Summary: Ref T13202. See <https://discourse.phabricator-community.org/t/2fa-input-box-isnt-hinted-as-a-password-so-browsers-suggest-auto-fills/1959>. If browsers are autofilling this, I think browser behavior here is bad, but behavior is probably better on the balance if we hint this as `autocomplete="off"` and this is a minor concesssion. Test Plan: - I couldn't immediately get any browser to try to autofill this field (perhaps I've disabled autofill, or just not enabled it aggressively?), but this change didn't break anything. - After the change, answered a TOTP prompt normally. - After the change, inspected page content and saw `autocomplete="off"` on the `<input />` node. Reviewers: amckinley Reviewed By: amckinley Maniphest Tasks: T13202 Differential Revision: https://secure.phabricator.com/D19722