Use the correct type (integer) for the `$menu_id` parameter in the `wp_get_nav_menu_to_edit()` DocBlock.

Also properly mark the parameter as optional and specify the default value.

Props jaimieolmstead for the initial patch.
Fixes #30540.


git-svn-id: https://develop.svn.wordpress.org/trunk@30627 602fd350-edb4-49c9-b593-d223f7449a82
Add missing return descriptions for a variety of functions in wp-includes/link-template.php.

Props colorful-tones, dustyf.
See #30406.


git-svn-id: https://develop.svn.wordpress.org/trunk@30628 602fd350-edb4-49c9-b593-d223f7449a82
Check attachments as well as the current post type when checking for duplicate post slugs. This avoids creating a page with a slug which conflicts with an existing attachment (the inverse is already handled).

Updates the existing test for pages which should take priority over attachments in cases where an existing clash exists.

Fixes #18962
Props boonebgorges


git-svn-id: https://develop.svn.wordpress.org/trunk@30629 602fd350-edb4-49c9-b593-d223f7449a82
Add missing DocBlocks for several functions in wp-admin/includes/ms.php.

Props dustyf.
See #30483.


git-svn-id: https://develop.svn.wordpress.org/trunk@30630 602fd350-edb4-49c9-b593-d223f7449a82
WPDB Unit Tests: Fix a fatal error that occurs in the `test_strip_invalid_text()` test if the `mbstring` extension isn't activated in PHP.


git-svn-id: https://develop.svn.wordpress.org/trunk@30631 602fd350-edb4-49c9-b593-d223f7449a82
Document the `$user_id` parameter added to the 'admin_color_scheme_picker' hook in 3.8.1.

Props Ipstenu.
Fixes #30551.


git-svn-id: https://develop.svn.wordpress.org/trunk@30632 602fd350-edb4-49c9-b593-d223f7449a82
Remove return descriptions from the DocBlocks for `add_image_size()` and `set_post_thumbnail_size()` as they don't return anything.

Also document the `$_wp_additional_image_sizes` global, leveraged in `add_image_size()`.

Props stevegrunwell.
Fixes #30511.


git-svn-id: https://develop.svn.wordpress.org/trunk@30633 602fd350-edb4-49c9-b593-d223f7449a82
Upgrade to MediaElement 2.16.2
https://github.com/johndyer/mediaelement/compare/2.15.1...2.16.2

Fixes #30281.


git-svn-id: https://develop.svn.wordpress.org/trunk@30634 602fd350-edb4-49c9-b593-d223f7449a82
Remove an invalid parameter from the DocBlock for the `gallery_style` hook.

Props keesiemeijer.
Fixes #30507.


git-svn-id: https://develop.svn.wordpress.org/trunk@30635 602fd350-edb4-49c9-b593-d223f7449a82
Ensure uniqueness when returning page lists in `get_page_children()`. Fixes failing unit tests.

Props boonebgorges.
Reverts [30246].
Fixes #14477.


git-svn-id: https://develop.svn.wordpress.org/trunk@30636 602fd350-edb4-49c9-b593-d223f7449a82