Logged out warnings: add fallback text dialog for:
- The login page has "X-Frame-Options: DENY" header.
- Cross-domain when displaying on the front-end on multisite with domain mapping.
- The site forces ssl login but not ssl admin.

Add onbeforeunload prompt to counter (frame-busting) JS redirects. Move the JS and CSS into separate files. See #23295.

git-svn-id: http://core.svn.wordpress.org/trunk@23805 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Drop the_chat() into twentythirteen. Style updates to follow — just wanted the_chat() to be utilized somewhere.

props lancewillett. see #23869

git-svn-id: http://core.svn.wordpress.org/trunk@23806 1a063a9b-81f0-0310-95a4-ce76da25c4cd