Point "current time" definition to hr-time "current high resolution time" algorithm

Based on the updated "current time high resolution time" on the [hr-time spec](https://w3c.github.io/hr-time/#dfn-current-high-resolution-time).

We should update the definition for [current time](https://w3c.github.io/resource-timing/#dfn-current-time) to point to the algorithm defined in the correct way.