height property Null safety

1. jrpn
2. view.main_screen
3. ScreenPositioner
4. height property

ScreenPositioner class

1. Constructors
2. ScreenPositioner
3. Properties
4. hashCode
5. height
6. runtimeType
7. width
8. Methods
9. box
10. noSuchMethod
11. toString
12. Operators
13. operator ==