This is the password visual hashing code for Privacy Watchdog. This add-on injects javascript into every password input element that causes the background of the input to change to a four color bar corresponding to a hash of the user's password. By memorizing your password's visual hash, you can know if you've entered your password correctly without having to display your password on screen.
This is available as both a Jetpack add-on for Firefox, and as a Google Chrome extension.