Fix the invalid markup generated by the printer icon.

islandora.module

@@ -1940,6 +1940,8 @@ function islandora_menu_local_tasks_alter(&$data, $router_item, $root_path) {
         if ($tab['#link']['path'] == 'islandora/object/%/print_object') {
           if ($root_path == 'islandora/object/%') {
             $islandora_path = drupal_get_path('module', 'islandora');
+            $tab['#prefix'] = '<li>';
+            $tab['#suffix'] = '</li>';
             $tab['#theme'] = 'link';
             $tab['#text'] = theme('image', array(
               'path' => "$islandora_path/images/print-icon.png",