DiagnosticsTreeStyle constructor Null safety

1. Flutter
2. foundation
3. DiagnosticsTreeStyle
4. DiagnosticsTreeStyle const constructor

DiagnosticsTreeStyle enum

1. Constructors
2. DiagnosticsTreeStyle
3. Values
4. none
5. sparse
6. offstage
7. dense
8. transition
9. error
10. whitespace
11. flat
12. singleLine
13. errorProperty
14. shallow
15. truncateChildren
16. Properties
17. hashCode
18. index
19. runtimeType
20. Methods
21. noSuchMethod
22. toString
23. Operators
24. operator ==
25. Constants
26. values