Drop dom.enable_resource_timing = false preference

spun off from #41496 (comment 2950524)

thorin

tom has spoken

No performance APIs should be disabled when RFP is enabled and all timestamps in all performance APIs (and all APIs in general) should have > consistent timestamp clamping+jittering.

FYI - your performance APIs

But, I do remember something about resource_timing being special - so IDK, you need to ask tom

pierov

I'd be okay with leaving it for now, and opening an issue for 13.5. If we confirm it's good, we add the reference and stop thinking about it for a while.

cc: @pierov