This requires a few adjustments of time zone names and offsets in some
places. The only named time zone that is required to be supported by an
implementation not supporting ECMA-402 is "UTC".
In order to test this functionality on hosts that don't have Intl, we have
to use "UTC" and offset-only time zones here, as the full set of IANA time
zone names are not required to be supported across all hosts.
This makes some progress on https://github.com/tc39/test262/issues/3253
Nails down intended behavior of `PlainDate` and
`PlainDateTime`'s `since` that is already true in the
polyfill but which was specified in a buggy way (and hence
potentially not true in an implementation of Temporal).
Add similar tests for Instant, PlainTime, PlainYearMonth, and
ZonedDateTime.
Reference:
https://github.com/tc39/proposal-temporal/pull/1881
Tests for the normative changes made to Temporal in
https://github.com/tc39/proposal-temporal/pull/1873
This adds a new Temporal helper calendar that asserts that its dateAdd()
method is always called with a PlainDate instance. This allows testing
that relativeTo parameters are always converted to PlainDate if they are
not ZonedDateTime and not undefined. Prior to the normative PR, they
would be converted to PlainDateTime instead.
Additionally and optionally, the helper calendar can also assert that its
dateAdd() method is called with a specific PlainDate instance. This allows
testing that the instance is the same PlainDate passed as the relativeTo
parameter (in the case of Duration methods) or is the receiver (in the
case of PlainDate methods). For the PlainDateTime and PlainYearMonth
methods the PlainDate instance is synthesized internally so there is no
need to assert that dateAdd() is called with a specific instance.
Move part of the test of toLocaleString which depends on
15 Amendments to the ECMAScript® 2021 Internationalization API Specification
to intl402. Keep behavior specified in earlier chapters in built-ins
