Update: Decoder performance analysis on mobile devices (ACTION-116)

A quick update on the WOFF 2.0 decoder performance analysis action item:
http://www.w3.org/Fonts/WG/track/actions/116

Kenji created a tracking bug to add the necessary instrumentation in Chrome
to collect the data.  Please review:
https://code.google.com/p/chromium/issues/detail?id=447127

Once the instrumentation reaches Chrome stable (which would take time), we
would be able to drill in by desktop/mobile.

Thank you Kenji and team!