function hasLocale(requestedLocale) {
  // The default locale is always supported through `IcuMessage.formattedDefault`.
  if (requestedLocale === DEFAULT_LOCALE) return true;

  const hasIntlSupport = Intl.NumberFormat.supportedLocalesOf([requestedLocale]).length > 0;
  const hasMessages = Boolean(LOCALE_MESSAGES[requestedLocale]);

  return hasIntlSupport && hasMessages;
}
Returns whether the `requestedLocale` is registered and available for use
@param {LH.Locale} requestedLocale
@return {boolean}