If a common browser protocol required the password to be salted with an application supplied value and then rehashed with the domain name it's served on, there'

If a common browser protocol required the password to be salted with an application supplied value and then rehashed with the domain name it's served on, there'd be no way to phish a password. The value the user's browser sends back can't be reversed, so any website prompting from the wrong domain would only ever see an incorrect hash, rather then the cleartext as it does now.