Layer class

1. Constructors
2. Layer
3. Properties
4. alwaysNeedsAddToScene
5. debugCreator
6. debugSubtreeNeedsAddToScene
7. nextSibling
8. parent
9. previousSibling
10. attached
11. depth
12. hashCode
13. owner
14. runtimeType
15. Methods
16. addToScene
17. adoptChild
18. debugFillProperties
19. debugMarkClean
20. dropChild
21. find
22. markNeedsAddToScene
23. remove
24. replaceWith
25. toStringShort
26. updateSubtreeNeedsAddToScene
27. attach
28. debugDescribeChildren
29. detach
30. noSuchMethod
31. redepthChild
32. redepthChildren
33. toDiagnosticsNode
34. toString
35. toStringDeep
36. toStringShallow
37. Operators
38. operator ==