This issue is to track aligning Lighthouse's implementation of TTI with the latest draft version proposed by the Chrome Speed Metrics team (at a time when we feel comfortable making that change).

Change in definition: Google internal doc defining firstInteractive

The best definition so far was 'firstInteractive-FMP-ReverseSearchFromNetworkFirstInteractive', which does the reverse search from network first interactive.

WebPageTest definition (closer to the above) from Pat Meenan

cc @tdresser