Autosave: use heartbeat to determine when connection is lost and disable the Save and Publish buttons. Re-enable the buttons when connection is restored. Props dh-shredder, see #23220

git-svn-id: http://core.svn.wordpress.org/trunk@23886 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Compress scripts/styles: 3.6-alpha-23887.

git-svn-id: http://core.svn.wordpress.org/trunk@23887 1a063a9b-81f0-0310-95a4-ce76da25c4cd