Better standardize parameter value types in PHPDocs where both a post ID or `WP_Post` would be acceptable.

Covers cases where previously only `int` or `int|object` types were notated.

Props coffee2code for the original patch.
See #20495.


git-svn-id: https://develop.svn.wordpress.org/trunk@27473 602fd350-edb4-49c9-b593-d223f7449a82