Fix Range#size return type to Int32

[straight-shoota]

Resolves #14587

The super implementation Enumerable#size has the same type restriction already.

See also #13648 (comment)

[straight-shoota]

Hm, actually this can overflow on ranges of Int types that are bigger than Int32 🤔
Should we only cast to Int32 on smaller types?

[beta-ziliani]

I'm afraid there's no good solution here. The good part of raising on overflow is that if it fits, it works. The bad part is that the failure is at runtime...

An alternative, as good or bad, is to statically fail on > Int32 types and have people do the math themselves 🤷