Add "experimental" to heartbeat phpdoc, fixes #24855 for 3.6.

git-svn-id: https://core.svn.wordpress.org/branches/3.6@24819 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Remove our revisions easter egg, as it doesn't have a place in our new UI.

There will be opportunities for other easter eggs. This one has had its decade.

Fixes #24852 for 3.6. Props noahsilverstein.

git-svn-id: https://core.svn.wordpress.org/branches/3.6@24821 1a063a9b-81f0-0310-95a4-ce76da25c4cd