Revisions: Don't pin controls to the top in IE 7.

Seriously IE 7 users, this is more consideration than your browser deserves. You can thank us by upgrading.

See #24736. Props adamsilverstein.

git-svn-id: http://core.svn.wordpress.org/trunk@24772 1a063a9b-81f0-0310-95a4-ce76da25c4cd