[webappsec] new UISecurity draft for Monday

I'll send out a more detailed agenda soon, but I've just pushed a new
editor's draft of UISecurity and the Visibility API based on the strategies
that Dan Kaminsky discussed with us a few meetings ago.

http://w3c.github.io/webappsec/specs/uisecurity/index.html

It's very rough in terms of spec editorial polish, cross-linking, etc., but
hopefully gives enough of an idea of the algorithms, changes, and new API
surface to have a good discussion.

Will send out an agenda for our last noon, PST call tomorrow.

-Brad