PSA: requestAnimationFrame & DocumentTImeline timestamps time are now coarsensed

[Noam Rosenthal]

As of Chrome M120, the timestamps passed to the requestAnimationFrame() callback and the timestamp returned by document.timeline.currentTime would be coarsened according to the rules specified in https://w3c.github.io/hr-time/#dfn-coarsen-time/. This means that in cross-origin isolated contexts, those timestamps would have a resolution of 5 microseconds. Coarsening these timestamps is aligned with current Gecko & WebKit behavior (WebKit aligns those timestamps to a whole millisecond), and is specified in the HTML standard.

Authors that rely on these timestamps to be super-high-resolution in Chromium should now expect them to be slightly coarser