Properly check if the custom header/background has been initialized. fixes #23170. see #22246.

git-svn-id: http://core.svn.wordpress.org/trunk@23367 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Correct the documentation for balanceTags(). Remove unnecessary boolean inversion. props TobiasBg. fixes #22537.

git-svn-id: http://core.svn.wordpress.org/trunk@23368 1a063a9b-81f0-0310-95a4-ce76da25c4cd
New icons take one, props empireoflight, see #23333

git-svn-id: http://core.svn.wordpress.org/trunk@23369 1a063a9b-81f0-0310-95a4-ce76da25c4cd