isAbstract property Null safety

1. Flutter
2. vm_service
3. Func
4. isAbstract property

Func class

1. Constructors
2. Func
3. Properties
4. classRef
5. code
6. fixedId
7. hashCode
8. id
9. implicit
10. isAbstract
11. isConst
12. isStatic
13. json
14. location
15. name
16. owner
17. runtimeType
18. signature
19. size
20. type
21. Methods
22. noSuchMethod
23. toJson
24. toString
25. Operators
26. operator ==
27. Static methods
28. parse