* lisp/outline.el (outline-minor-mode-cycle--bind): Fix outline-on-heading-p.

* lisp/outline.el (outline-minor-mode-cycle--bind): Fix outline-on-heading-p.

When calling outline-on-heading-p, set its argument INVISIBLE-OK to t,
so when <backtab> (bound to outline-cycle-buffer) hides the current outline
at a deep level, <backtab> should continue cycling outlines even when
the current outline heading is invisible.  It worked this way before
the recent change that moved cycling keys from font-lock text properties
to outline-minor-mode keymap with :filter.