Change whitelist invite form's add new item control to be consistent with similar controls elsewhere

plugins/DomainWhitelist/lib/whitelistinviteform.php

@@ -152,19 +152,10 @@ class WhitelistInviteForm extends Form
                 'class' => 'add_row',
                 'href'  => 'javascript://',
             ),
-            '+'
+            _m('Add another item')
         );
     }
         
-    function getUsersDomain()
-    {
-        $user = common_current_user();
-        
-        assert(!empty($user));
-        
-        
-    }
-    
     /**
      * Action elements
      *