(as of Oct 11)
Resource Timing says:
"...the user agent must record the system clock at the beginning of the * root* document navigation..."
High Resolution Time says:
"...the number of milliseconds from the navigationStart attribute of the PerformanceTiming interface, the start of navigation of *the* document..."
So in iframes, Resource Timing will be offset, but now() won't be. That seems bad. We should be consistent.
As one of the headlining features about web workers is to use them for performance gains it makes sense to expose the sub-millisecond resolution `now` function to web workers. As has been discussed numerous times, Date.now is unreliable and inaccurate even at the millisecond resolution and these inaccuracies can have a strong impact on performance- and accuracy-sensitive applications.