PerformanceApiAdapter

Mirrors the editor's timing events into the browser's own Performance timeline, and collects long-animation-frame reports.

The point is that a person profiling a canvas should see the editor's spans — "translating", "camera", "frame" — in the same devtools flame chart as everything else, instead of having to correlate two timelines by eye. It writes performance.mark / performance.measure entries and nothing else; it never reports anywhere, and it holds no reference to the document.

Construct one against editor.performance and call dispose when the editor goes away.