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.

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Add missing return descriptions for a variety of functions in wp-includes/link-template.php.

Props colorful-tones, dustyf.
See #30406.

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git-svn-id: http://core.svn.wordpress.org/trunk@30618 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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

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git-svn-id: http://core.svn.wordpress.org/trunk@30619 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add missing DocBlocks for several functions in wp-admin/includes/ms.php.

Props dustyf.
See #30483.

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git-svn-id: http://core.svn.wordpress.org/trunk@30620 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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.

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git-svn-id: http://core.svn.wordpress.org/trunk@30621 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Document the `$user_id` parameter added to the 'admin_color_scheme_picker' hook in 3.8.1.

Props Ipstenu.
Fixes #30551.

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git-svn-id: http://core.svn.wordpress.org/trunk@30622 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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.

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git-svn-id: http://core.svn.wordpress.org/trunk@30623 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Upgrade to MediaElement 2.16.2
https://github.com/johndyer/mediaelement/compare/2.15.1...2.16.2

Fixes #30281.

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git-svn-id: http://core.svn.wordpress.org/trunk@30624 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Remove an invalid parameter from the DocBlock for the `gallery_style` hook.

Props keesiemeijer.
Fixes #30507.

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git-svn-id: http://core.svn.wordpress.org/trunk@30625 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Ensure uniqueness when returning page lists in `get_page_children()`. Fixes failing unit tests.

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

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git-svn-id: http://core.svn.wordpress.org/trunk@30626 1a063a9b-81f0-0310-95a4-ce76da25c4cd
IETF language changes in MediaElement:
https://github.com/johndyer/mediaelement/pull/1270/

Reverts [28801].
Fixes #29182.

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git-svn-id: http://core.svn.wordpress.org/trunk@30627 1a063a9b-81f0-0310-95a4-ce76da25c4cd
When deleting media grid attachments, wait until the server responds before removing the model from its collection.

Props 5um17.
Fixes #30457.

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git-svn-id: http://core.svn.wordpress.org/trunk@30628 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Fix edge-case in media cropping where selection and destination are the same size.

Adds unit tests.

Props mboynes.
Fixes #19793.

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git-svn-id: http://core.svn.wordpress.org/trunk@30629 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Adjust the RegEx in `wp_check_filetype()` to be aware that query strings are thing that exist sometimes in URLs.

Adds unit tests.

Props voldemortensen.
Fixes #30377.

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git-svn-id: http://core.svn.wordpress.org/trunk@30630 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Editor: no pointer for DFW v2 when editor-scrolling is not used. Pass `$post_type` in the `wp_editor_expand` filter. See #30458.
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