RFC: WebApp timing

Hello,

   We recently started a draft to provide timing-related APIs in browsers.
The goal is to add the missingpieces in webapp latency measurements using
Javascript. As a starter, right now we've only include a
minimum set of interfaces we consider necessary, which mainly focuse on the
time and type of the
navigation.

   The first cut of the draft is attached below. It's sketchy but should
hold much of our ideas. We are
still actively working on it. Any interest and feedback on the draft are
highly welcome.

cheers,
Zhiheng