Implement https://github.com/tc39/ecma402/pull/487
Also improve test/intl/toStringTag.js

see also: https://github.com/tc39/test262/pull/2712

Bug: v8:10744
Change-Id: I678876aa21f169a8dfcec8e3ce974978a8847fe0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2315455Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69185}