Missing timeline events in performance data export

A few things I noticed:
* Timeline events only show up in the exported data if the timeline events if the "Timeline Events" tab in the performance panel has been clicked and loaded.
* Additionally, sometimes a frame needs to be selected first before the events show up in the export.

Reproduce the export from the performance panel without opening the "Timeline Events" tab or selecting a frame, then compare it with an export after loading that tab. Trace the performance panel's timeline-event loading and export entry points to identify why the exported data differs. Done means timeline events appear consistently without those preparatory UI actions.

Scritto dal modello di indicizzazione a partire dal testo della issue.