Fix checkbox synchronization on Edit Link screen. fixes #23670.

git-svn-id: http://core.svn.wordpress.org/trunk@23586 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Remove unused function. fixes #23671.

git-svn-id: http://core.svn.wordpress.org/trunk@23587 1a063a9b-81f0-0310-95a4-ce76da25c4cd