WidgetInspectorService mixin

1. Constructors
2. WidgetInspectorService
3. Properties
4. selection
5. selectionChangedCallback
6. hashCode
7. runtimeType
8. Methods
9. disposeAllGroups
10. disposeGroup
11. disposeId
12. forceRebuild
13. getChildren
14. getChildrenDetailsSubtree
15. getChildrenSummaryTree
16. getDetailsSubtree
17. getParentChain
18. getProperties
19. getRootRenderObject
20. getRootWidget
21. getRootWidgetSummaryTree
22. getSelectedRenderObject
23. getSelectedSummaryWidget
24. getSelectedWidget
25. initServiceExtensions
26. isWidgetCreationTracked
27. isWidgetTreeReady
28. performReassemble
29. postEvent
30. registerServiceExtension
31. screenshot
32. setPubRootDirectories
33. setSelection
34. setSelectionById
35. toId
36. toObject
37. toObjectForSourceLocation
38. noSuchMethod
39. toString
40. Operators
41. operator ==
42. Static properties
43. instance