Benchmark script execution performance.

[joeyhub]

It would be nice to include in the benchmark scripts some benchmarks of the scripts after they are minified to also account for optimisations.

Minimal:

• Run time for a single function that gives high coverage.
• If it's a standard JS lib being tested, run it's own included tests as a benchmark?

OTT?

• Run time for a variety of functions.
• More detailed timings (min/max/avg).
• Memory/CPU usage.

Throw in the full INTL / ICU lib for fun?