Remove some unused dashboard-widget-* CSS classes. Unused since [9103].

props michalzuber.
fixes #28930.
Built from https://develop.svn.wordpress.org/trunk@29361


git-svn-id: http://core.svn.wordpress.org/trunk@29137 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add blog_id to the `wp-settings-*` cookie (used for storing user state) to prevent it being overloaded on sub-domain sites. Fixes #29095.
Built from https://develop.svn.wordpress.org/trunk@29362


git-svn-id: http://core.svn.wordpress.org/trunk@29138 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add an action, `pre_get_users`, in `WP_User_Query::prepare_query()`.

Props rmccue.
Fixes #29084.

Built from https://develop.svn.wordpress.org/trunk@29363


git-svn-id: http://core.svn.wordpress.org/trunk@29139 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Modal: Restore uploader view, when no items are found.

see #28963.
Built from https://develop.svn.wordpress.org/trunk@29364


git-svn-id: http://core.svn.wordpress.org/trunk@29140 1a063a9b-81f0-0310-95a4-ce76da25c4cd