[#34058] Wrong css-class in user-registration tooltip

http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=34058
After patch


![screen shot 2014-08-11 at 12 28 32](https://cloud.githubusercontent.com/assets/869724/3874485/4c297e40-2142-11e4-9ddd-2c6baf7e4ba8.png)