gFlag property Null safety

1. jrpn
2. model
3. DoubleWordStatus
4. gFlag property

DoubleWordStatus class

1. Constructors
2. DoubleWordStatus
3. Properties
4. cFlag
5. gFlag
6. hashCode
7. integerSignMode
8. isFloatMode
9. maxInt
10. minInt
11. runtimeType
12. signMask
13. wordMask
14. wordSize
15. Methods
16. noSuchMethod
17. toString
18. Operators
19. operator ==