* Change the logic to reflect the spec change of
  https://github.com/tc39/proposal-intl-datetime-style/pull/37/
* Move enum value of kUndefined to 0 to make unset behavior the same as
  kUndefined.
* Change the expectation of existing tests
* Additional tests - https://github.com/tc39/test262/pull/2385

Bug: v8:9826
Change-Id: Ic437b5f6414aa641ae73766d8c5fd5b9d352a230
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1846722Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64255}