collapseToStart method Null safety

1. Flutter
2. dart:html
3. Selection
4. collapseToStart method

Selection class

1. Properties
2. anchorNode
3. anchorOffset
4. baseNode
5. baseOffset
6. extentNode
7. extentOffset
8. focusNode
9. focusOffset
10. hashCode
11. isCollapsed
12. rangeCount
13. runtimeType
14. type
15. Methods
16. addRange
17. collapse
18. collapseToEnd
19. collapseToStart
20. containsNode
21. deleteFromDocument
22. empty
23. extend
24. getRangeAt
25. modify
26. noSuchMethod
27. removeAllRanges
28. removeRange
29. selectAllChildren
30. setBaseAndExtent
31. setPosition
32. toString
33. Operators
34. operator ==