Avoid resolving types when checking subtyping on structs. This fixes problems with caching, because sometimes we were giving the wrong answer for nested calls to `subtype'.
Avoid resolving types when checking subtyping on structs.
This fixes problems with caching, because sometimes we were giving the wrong answer for nested calls to `subtype'.

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket