superClass property Null safety

1. Flutter
2. vm_service
3. Class
4. superClass property

Class class

1. Constructors
2. Class
3. Properties
4. classRef
5. error
6. fields
7. fixedId
8. functions
9. hashCode
10. id
11. interfaces
12. isAbstract
13. isConst
14. json
15. library
16. location
17. mixin
18. name
19. runtimeType
20. size
21. subclasses
22. superClass
23. superType
24. traceAllocations
25. type
26. typeParameters
27. Methods
28. noSuchMethod
29. toJson
30. toString
31. Operators
32. operator ==
33. Static methods
34. parse