Provide hook for getting a high resolution time between time origin and a "time"

[annevk]

The DOM Standard currently creates a DOMHighResTimeStamp representing the high resolution time from the time origin to the time of the occurrence that the event is signaling.

"[T]he time of the occurrence that the event is signaling" is really the only thing that the DOM Standard should define here (or callers). The remainder should be a reference to a concept in this document that does the correct thing. I.e., something that "current high resolution time" also builds upon.

[igneel64]

Proposing the "relative high resolution time" definition which would construct the high resolution time based on a specific time input.
Exporting it so the DOM Standard can use it in the proposed way.