diff -Naur wp-admin/includes/misc.php wp-admin/includes/misc.php
--- wp-admin/includes/misc.php	2018-04-03 11:10:07.462160000 +0530
+++ wp-admin/includes/misc.php	2018-04-03 11:23:11.955827185 +0530
@@ -304,6 +304,9 @@
  * @since 4.9.0
  * @access private
  *
+ * @global string $relative_file Filename. 
+ * @global string $stylesheet Stylesheet. 
+ *
  * @param array|string $tree  List of file/folder paths, or filename.
  * @param int          $level The aria-level for the current iteration.
  * @param int          $size  The aria-setsize for the current iteration.