In `customize.php`, check that `$autofocus` is an `array` after running `wp_unslash()` instead of before. This is admittedly to skip a traversable hint in Scrutinizer.

See #30224.


git-svn-id: https://develop.svn.wordpress.org/trunk@30164 602fd350-edb4-49c9-b593-d223f7449a82