The https://github.com/paulirish/devtools-timeline-model that has a couple of bugs (reporting too low scripting time and unclear detailed scripting report). I've reported it upstream and I can ping Paul Irish in a couple of days (Lighthouse uses the same library internally so they also have the same problem).
We can try out the trace parser that WebPageTest uses, it is Open Source and broken out of WebPageTest https://github.com/WPO-Foundation/trace-parser
It will need some more work: The parser generates a new JSON file that we need to parse again and map each event against each category (scripting/rendering etc) but we already do that in the WebPageTest wrapper so we can reuse that.
