After [28883], ensure that priorities have callbacks before returning `true` in `has_filter()`.

Adds unit tests.

Props boonebgorges.
Fixes #29070.

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`WP_List_Table::items` should be `public`, not `protected`. It is accessed in a subclass directly via `wp_ajax_get_comments()`.

See [28493].
Fixes #29072.

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git-svn-id: http://core.svn.wordpress.org/trunk@29201 1a063a9b-81f0-0310-95a4-ce76da25c4cd
After [29201], use `aria-label` instead of `aria-labelledby` in `WP_Plugin_Install_List_Table::display_rows()`.

Props nvwd, DrewAPicture.
Fixes #28853.

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git-svn-id: http://core.svn.wordpress.org/trunk@29202 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Grid: reduce the padding for `.attachments`.

Props ocean90, ryelle.
Fixes #29085.

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git-svn-id: http://core.svn.wordpress.org/trunk@29203 1a063a9b-81f0-0310-95a4-ce76da25c4cd
In `media.view.AttachmentFilters.All`, make `uploaded` conditional upon `media.view.settings.post.id` and include a new filter: `unattached`.

Drop the `mime-types` filter and related class (which was added for Media Grid) and use `all` instead. 

Props ocean90, wonderboymusic.
Fixes #29065.

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git-svn-id: http://core.svn.wordpress.org/trunk@29204 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Grid: remove some unused Trash/Delete handler logic. Rendered useless since [29266] and made official by [29322].

See #28819.

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Media Grid: add screen reader labels with more context to filters and bulk actions. Ditto for list view.

Props afercia.
Fixes #29026.

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git-svn-id: http://core.svn.wordpress.org/trunk@29206 1a063a9b-81f0-0310-95a4-ce76da25c4cd
MediaElement upgrade: cleanup for generated markup for videos. 

See #29110.

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Video: use `auto` instead of actual height for the responsive wrapper in generated markup.

See #29110.

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