DevTools performance page doesn't detect jank between frames

In this example, the running app (Wonderous in profile mode) visibly janks, but there are no janky frames in the DevTools performance page. Upon looking deeper into the timeline trace, it is clear that there is a large gap of latency between two frames:

How is a user supposed to debug the jank at this point? How can we help them understand what could be causing the latency between frames?

CC @chinmaygarde @dnfield @iskakaushik @jonahwilliams for ideas.

Start by reproducing the Wonderous profile-mode jank in the DevTools performance page and compare the page's frame detection with the timeline trace shown in the issue. Trace how gaps between frames are represented and reported; done means the page identifies or explains this latency so users can investigate the jank.

Rédigé par le modèle d'indexation à partir du texte de l'issue.