Prefs: Don't present "-//W3C//DTD HTML 5//EN" as a possible Public ID for HTML documents, as HTML5 is a separate language (with no public ID).
http://bugs.activestate.com/show_bug.cgi?id=99783

(integrated from komodo (trunk) change 81408 by ericp)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@13434 b87d16e7-d29f-4ee1-b5ec-817d645d335f