Themes: Always include the current theme in the list, even if it is not allowed.

see #25948.


git-svn-id: https://develop.svn.wordpress.org/trunk@26529 602fd350-edb4-49c9-b593-d223f7449a82
Heartbeat: update wp-auth-check to use the new "connectNow()" method after a successful login, see #25073.

git-svn-id: https://develop.svn.wordpress.org/trunk@26530 602fd350-edb4-49c9-b593-d223f7449a82