Add missing Dashicons classes to User Admin menu.

Merges [28284] to the 3.9 branch.

props imath.
fixes #28144, #26630.


git-svn-id: https://develop.svn.wordpress.org/branches/3.9@28344 602fd350-edb4-49c9-b593-d223f7449a82
3.9.1


git-svn-id: https://develop.svn.wordpress.org/branches/3.9@28345 602fd350-edb4-49c9-b593-d223f7449a82