Add test cases for fixed PRs.

Closes PR 13191.
Closes PR 13290.

pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/unit-tests/contract-tests.rkt

@@ -81,6 +81,7 @@
 
               (t (-mu x (-Syntax x)))
               (t (-> (-> Univ -Bottom : -bot-filter) -Bottom : -bot-filter))
+              (t (-poly (A B) (-> A B (Un A B))))
 
 
               (t/fail ((-poly (a) (-vec a)) . -> . -Symbol)

pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/unit-tests/typecheck-tests.rkt

@@ -2667,6 +2667,18 @@
            (number? x))
          -Boolean]
 
+       [tc-e/t
+         (let ()
+           (: f (Number -> Number))
+           (define (f x)
+             (cond
+               ((zero? x) x)
+               (else (add1 (f (sub1 x))))))
+
+           (define y (f 7))
+           4)
+         -PosByte]
+
         )
   (test-suite
    "tc-literal tests"