Make testing for headline independent of visibility

lisp/ChangeLog

@@ -1,5 +1,8 @@
 2009-09-18  Carsten Dominik  <carsten.dominik@gmail.com>
 
+	* org.el (org-on-heading-p, org-at-heading-p): Make sure these are
+	always with `invisible-ok'.
+
 	* org-list.el (org-update-checkbox-count): Insert changed cookie
 	before the old, to avoid problems with invisibility at the end of
 	the line.

lisp/org.el

@@ -16781,8 +16781,11 @@ interactive command with similar behavior."
   (save-excursion
     (null (re-search-backward "^\\*+ " nil t))))
 
-(defalias 'org-on-heading-p 'outline-on-heading-p)
-(defalias 'org-at-heading-p 'outline-on-heading-p)
+(defun org-on-heading-p ()
+  (outline-on-heading-p t))
+(defun org-at-heading-p ()
+  (outline-on-heading-p t))
+
 (defun org-at-heading-or-item-p ()
   (or (org-on-heading-p) (org-at-item-p)))