Intl.DisplayNames v2 adds "calendar" and "dateTimeField" types, as well
as a "languageDisplay" option for the "language" type. This just adds
these options to the constructor.
Both at the same time because many of them call construct() in call()
and I'm not keen on adding a bunch of temporary plumbing to turn
exceptions into throw completions.
Also changes the return value of construct() to Object* instead of Value
as it always needs to return an object; allowing an arbitrary Value is a
massive foot gun.
The old versions were renamed to JS_DECLARE_OLD_NATIVE_FUNCTION and
JS_DEFINE_OLD_NATIVE_FUNCTION, and will be eventually removed once all
native functions were converted to the new format.
There is notably FIXME notations in this commit regarding Unicode locale
extensions. We are not parsing extensions (or private use extensions) at
all yet.
