hardware timestamp for DOM Events.

Continuing the discussion about Event.highResolutionTimestamp
(http://lists.w3.org/Archives/Public/www-dom/2012AprJun/0078.html)

It looks like a patch to WebKit is in progress for something along these lines:
https://bugs.webkit.org/show_bug.cgi?id=94987

I was toying with the idea of adding this to the UI Events spec, but as a core piece of eventing logic, it probably needs to be in DOM4 (on the Event interface).

Any preferences here?

-Travis