[WebAPI] Enable PerformanceEventTiming

[chrisdavidmills]

Acceptance criteria

1. • The listed features are documented sufficiently on MDN
2. • BCD is updated
3. • Interactive example and data repos are updated if appropriate
4. • The content has been reviewed as needed

Features to document

1. PerformanceEventTiming

Related Gecko bugs

1. • Enable PerformanceEventTiming in all channels. PerformanceEventTiming has an interface page and BCD. At the very least this would just require a BCD update, but it'd be nice to add the missing member pages too.

For folks helping with Firefox-related documentation features — make sure above AC have been done, but also:

• Set bugs to dev-doc-complete
• Add entry to Firefox release notes if feature is enabled in release
• Add entry to Firefox experimental features page if feature is not yet enabled in release

[chrisdavidmills]

I've added a rel note for this one — see 304f4e2 — so I think this can be considered done for the purposes of the Fx 89 release.