Implement the spec changes in https://github.com/tc39/ecma402/pull/430

Bug: v8:10554
Change-Id: I421d6feb94810027cf17ff58a4ec5357940ef44a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2212889Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68119}