Fix thickbox positioning if toolbar is not present.

fixes #26745.
Built from https://develop.svn.wordpress.org/trunk@27248


git-svn-id: http://core.svn.wordpress.org/trunk@27105 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Declare $wpdb->base_prefix.

props DavidAnderson.
fixes #16762.

Built from https://develop.svn.wordpress.org/trunk@27249


git-svn-id: http://core.svn.wordpress.org/trunk@27106 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Use ext/mysqli in PHP 5.5 or greater. Expect minor explosions.

props aaroncampbell, pento.
see #21663.

Built from https://develop.svn.wordpress.org/trunk@27250


git-svn-id: http://core.svn.wordpress.org/trunk@27107 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Consistently return a WP_Error object in case of an error in wp_update_nav_menu_item().

props bootsz, ocean90.
fixes #21652.
Built from https://develop.svn.wordpress.org/trunk@27251


git-svn-id: http://core.svn.wordpress.org/trunk@27108 1a063a9b-81f0-0310-95a4-ce76da25c4cd