Face not work on outline buffer unless load the org feature

[sunlin7]

Hi, the outline face will not work until org feature been loaded. Here is reproduce steps:

1. Start emacs -q , and load the spacemacs-theme, apply the spacemacs-dark theme;
2. Open a file /tmp/a and M-x outline-mode, type follow two lines, the outline face does not work:

* a0
** a1

For comparison, the outline-face will work:
a) Without applying the spacemacs-dark, the emacs builtin theme will work directly with the outline mode. Or,
b) (require 'org) will let the spacemacs-dark theme works on outline-mode buffers.

Please consider fix the issue, thanks