backup passphrase should not be required to save a key.

do not display the passphrase field unless it is expanded. (firefox has an annoying feature that activates when password field is focused.)

remove this text, it is unnecessary:
Use it on another device or after clearing this browser, with no new approval and your messages intact. The passphrase can't be recovered if you forget it.
(or hide in the help layer, when that is developed.)