supportedLocals property Null safety

1. baguette
2. i18n
3. I18nDelegate
4. supportedLocals property

I18nDelegate class

1. Constructors
2. I18nDelegate
3. Properties
4. hashCode
5. runtimeType
6. type
7. Methods
8. isSupported
9. load
10. noSuchMethod
11. shouldReload
12. toString
13. Operators
14. operator ==
15. Static properties
16. supportedLocals