Remove flags and all string in JSLocale
This does not change the logic of Intl.Locale constructor
but only the way we store the information.
Preparation for logic rewrite that sync with latest spec.

Bug: v8:7684
Change-Id: Ib61705eaf00e5bcf63443c55c29f0b0b61f8e4c9
Reviewed-on: https://chromium-review.googlesource.com/c/1377996
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58386}