KeyLocation constructor Null safety

1. Flutter
2. dart:html
3. KeyLocation
4. KeyLocation constructor

KeyLocation class

1. Constructors
2. KeyLocation
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. JOYSTICK
13. LEFT
14. MOBILE
15. NUMPAD
16. RIGHT
17. STANDARD