Color schemes should use .ab-icon:before instead of .ab-item:before to target adminbar icons. See #25858.

git-svn-id: https://develop.svn.wordpress.org/trunk@26181 602fd350-edb4-49c9-b593-d223f7449a82
Remove now-unused #adminmenushadow. see #25858.


git-svn-id: https://develop.svn.wordpress.org/trunk@26182 602fd350-edb4-49c9-b593-d223f7449a82