Locale constructor
Creates a new Locale object. The first argument is the primary language subtag, the second is the region subtag.
For example:
const Locale swissFrench = const Locale('fr', 'CH');
const Locale canadianFrench = const Locale('fr', 'CA');
The primary language subtag must not be null. The region subtag is optional.
The values are case sensitive, and should match the case of the relevant subtags in the IANA Language Subtag Registry. Typically this means the primary language subtag should be lowercase and the region subtag should be uppercase.
Implementation
const Locale(this._languageCode, [ this._countryCode ]) : assert(_languageCode != null);