Restore "Search Engines Discouraged" to the dashboard.

props JustinSainton.
fixes #26431.


git-svn-id: https://develop.svn.wordpress.org/trunk@26700 602fd350-edb4-49c9-b593-d223f7449a82
Fix z-indexes as it relates to thickbox, the theme modal, and admin menu.

props ryelle, shaunandrews.
fixes #26442.


git-svn-id: https://develop.svn.wordpress.org/trunk@26701 602fd350-edb4-49c9-b593-d223f7449a82