state property Null safety

1. Flutter
2. dart:html
3. MidiPort
4. state property

MidiPort class

1. Properties
2. connection
3. hashCode
4. id
5. manufacturer
6. name
7. on
8. runtimeType
9. state
10. type
11. version
12. Methods
13. addEventListener
14. close
15. dispatchEvent
16. noSuchMethod
17. open
18. removeEventListener
19. toString
20. Operators
21. operator ==