This is to fix an assertion failure in formatToParts when
Chinese calendar is specified with 'u-ca-chinese'.

See https://github.com/tc39/ecma402/issues/225 . This CL
is a temporary work-around to get v8 match the spec in terms
of the external behavior, but it's not taking the steps in
the spec, yet.

Moreover, the spec may have to be revised as to how to pick the best
match pattern when the default calendar for a locale is different from
the calendar specified via 'u-ca'. How to handle 'related year' part
also needs to be specified.

Bug: chromium:826549
Test: intl/date-format/format-with-extensions
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I1f9a2467e86e71e024bc9babe18f16e49746008e
Reviewed-on: https://chromium-review.googlesource.com/1006915Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jungshik Shin <jshin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52556}