Fix inconsistent id attributes. props kovshenin. fixes #24006.

git-svn-id: http://core.svn.wordpress.org/trunk@23939 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add alt attribute for selected image. see #19570.

git-svn-id: http://core.svn.wordpress.org/trunk@23940 1a063a9b-81f0-0310-95a4-ce76da25c4cd