Merge upstream PR #167: Conditionally show more metric details

See https://github.com/WebKit/JetStream/pull/167

- Collect and report subTimes like subScores
- Only show times if the global .details CSS class is set (the default view is unaffected)
- Also use .details for displaying displayCategoryScores
- Change uiFriendlyDuration to only report 2 significant digits
- Add Benchmark.prototype.wallTime accessor and report that as well
-  Use # as unit symbol for console printing

Change-Id: Ibc603b29c516060823c39c738069466cff57170a
Reviewed-on: https://chromium-review.googlesource.com/c/external/github.com/WebKit/JetStream/+/6976231
Reviewed-by: Victor Gomes <victorgomes@chromium.org>