Add some tests that check interaction between with-contract (here through define/contract) and unit contracts.
Add some tests that check interaction between with-contract (here
through define/contract) and unit contracts.

svn: r13183

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