do not use empty links

On lines 622 and 640 of vote_up_down.module the actual link text is left blank with ' ' and does not have 'Vote up' or 'Vote down' respectively.

The module appears to degrade gracefully when a user turns off JS but not when they are not using the CSS such as a visually impaired user who is using JAWS for instance.

I'd propose to change lines 622 and 640 to:

Before:

      $variables['link1'] = l('', "vote_up_down/$type/$cid/1/$tag", array(

      $variables['link2'] =  l('', "vote_up_down/$type/$cid/-1/$tag", array(

After:

      $variables['link1'] = l('Vote up', "vote_up_down/$type/$cid/1/$tag", array(

      $variables['link2'] =  l('Vote down', "vote_up_down/$type/$cid/-1/$tag", array(

Any thoughts? Shall we roll this up into a patch?