Currently things like `1 / 200` lead to a miscompilation because we type
`200` (and as a result, both `1` and the division result) as a ranged
number with width >= U8. During mono that forces the number to become an
`I64` because our logic was that a ranged number can only become a float
if it's at least as wide as an I8. But this is incorrect; as long as the
type is wrapped in `Frac` constructor and it's a ranged number (and not
a ranged int), it should become a fractional type.
```
» 1 / 200
0.005 : Float *
```
Closes#4047
a81d4d4be2