Adds formatRange() and formatRangeToParts() methods to Intl.DateTimeFormat to format a range of times between two dates, such as 'Jan 10 – 20, 2007', or 'Jan 10 – Feb 20, 2007'.
Docs: https://goo.gl/PGUQ1d
Samples: https://github.com/fabalbon/proposal-intl-DateTimeFormat-formatRange