I2S https://groups.google.com/a/chromium.org/forum/#!searchin/blink-dev/fractionalSecondDigits%7Csort:date/blink-dev/ISa0b6fOefY/pBlgkvZhBAAJ
I2P https://groups.google.com/a/chromium.org/forum/#!searchin/blink-dev/Intent$20to$20Implement$3A$20Add$20millisecondDigits$20option$20to$20Intl.DateTimeFormat%7Csort:date/blink-dev/WXd9nh03a1M/z7QeIMgrBgAJ
Chrome Status: https://www.chromestatus.com/feature/5704965743968256

Latest spec: https://github.com/tc39/ecma402/pull/347
LGTMs: bratell.d@gmail.com / chrishtr@chromium.org / mkwst@chromium.org

Bug: v8:9284
Change-Id: I4d2cca515ce65d41b38ebdef00b429fa873ea624
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2116989
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67381}