Adds detection for the existence of windown.Intl.

See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NumberFormat?redirectlocale=en-US&redirectslug=JavaScript%2FReference%2FGlobal_Objects%2FNumberFormat
Adds detection of argument support in Number.toLocaleString.

Probably detection of Intl suffices.