Sync with
https://github.com/tc39/proposal-intl-segmenter/pull/55
and
https://github.com/tc39/test262/pull/1994

Bug: v8:8588
Change-Id: Ifc46779f156ea986e3dbe6a632a781bb7134112b
Reviewed-on: https://chromium-review.googlesource.com/c/1374997Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58301}

Bug: v8:6891
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I0b82b194cb7089aeaa322ed4e45008db6890e7a1
Reviewed-on: https://chromium-review.googlesource.com/c/1266995Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56704}

Bug: v8:6891
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I075c4f615a4366c34723104410e8445054a3cacd
Reviewed-on: https://chromium-review.googlesource.com/c/1256867Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Daniel Ehrenberg <littledan@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56424}