Make sure torbutton_do_new_identity() is still working properly in ESR24
We should make sure that all mechanisms to clear state between to sessions are still doing their job. E.g. clearing the SSL session Id should not work anymore with the current code as logout() is gone in Fx 21 (https://bugzilla.mozilla.org/show_bug.cgi?id=683262) and "security.enable_ssl2" is gone long ago (even "security.enable_ssl3" is gone, in Fx 23).