Process.hrtime

node has Process.hrtime as a public-facing API call.  Although it's generally only used for benchmarking I have a need for nanosecondish timing precision.

The Process.hrtime in node returns a tuple of [seconds, nanoseconds], which I could make it do if you cared enough to make it match exactly.  As it is, this returns milliseconds as a 64 bit float directly as it is from uv_hrtime.