Re-initialize $wp_locale global after changing the default textdomain on installation screens.

props ocean90.
fixes #29452.
Built from https://develop.svn.wordpress.org/trunk@29669


git-svn-id: http://core.svn.wordpress.org/trunk@29443 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Use wp_admin_css() to enqueue stylesheets in setup-config.php.

fixes #29464.
Built from https://develop.svn.wordpress.org/trunk@29670


git-svn-id: http://core.svn.wordpress.org/trunk@29444 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Restore 'insert-media-button' as an ID attribute for the first instance of media_buttons(). Remove IDs for subsequent instances.

props nacin.
fixes #28090.
Built from https://develop.svn.wordpress.org/trunk@29671


git-svn-id: http://core.svn.wordpress.org/trunk@29445 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Menus: Improve performance for title live updating. Add `change` event for IE < 9.

props helen, SergeyBiryukov.
fixes #23076.
Built from https://develop.svn.wordpress.org/trunk@29672


git-svn-id: http://core.svn.wordpress.org/trunk@29446 1a063a9b-81f0-0310-95a4-ce76da25c4cd