Give my luck back, Firefox 5!

Today I've upgraded to firefox 5, special thanks to Debian developer for packaging it. So far, everything works well and better than before, except two things (one of which I managed to tweak):

1. The tabs bar is higher than before. This means that the mouse must move more to reach them. This has been solved. Thanks for allowing me to put the tabs bar below back again.
   
2. The address bar no more involves "I feel lucky" search. The feature was awesome, because I often write a partial website name and I get most of the time to the right page without actually typing the whole name. Also, since we already have a search bar on the top-right, why was this feature removed? It's kind of duplicated now.

So, dear readers, do you know of any add-on so that I can have "I feel lucky" search back, before I write one? Having it on the top-right bar is good as well.

Edit: The solution is to open about:config and set the keyword.URL value to "http://www.google.com/search?btnI=745&q=" (without quotes). Thanks to Giuseppe for the hint.