Registration page (ajax version): Resetting entered passwords, when passwords don't match

Password fields should be reset like in registration page, when passwords don't match

Steps to reproduce:

1. Click on Sign Up on the main jcommune page.
   Sign Up popup should be opened.
2. Enter different data into Password and confirm password fields and click Sign Up

Actual Result
Error message "Password and confirmation password do not match" is shown, but Password and Confirm Password fields still contain dots
Expected Result
Error message is shown and Password and Confirm Password fields are empty