reverted:
--- b/core/modules/file/file.js
+++ a/core/modules/file/file.js
@@ -133,4 +133,4 @@
       window.open(this.href, 'filePreview', 'toolbar=0,scrollbars=1,location=1,statusbar=1,menubar=0,resizable=1,width=500,height=550');
     }
   };
+})(jQuery, Drupal);
\ No newline at end of file
-})(jQuery, Drupal);