Fix a free variance bug

Commit ffe45ecce had introduced a regression with some
polymorphic functions imported between typed modules due to
miscommunicated variance information.

original commit: daca1c0d5b6040978b1c75d4cc822c0a3a819181

collects/tests/typed-racket/succeed/variance-test.rkt

@@ -0,0 +1,16 @@
+#lang typed/racket
+
+;; Test a variance regression
+
+(struct: (A) Foo ([elems : (Vectorof A)]))
+
+(: make-foo (All (A) (A -> (Foo A))))
+(define (make-foo x) (Foo (vector x)))
+
+;; Need a module+ here because this test failed
+;; originally when variance information wasn't preserved
+;; across modules.
+(module+ test
+  ;; should type check, but won't if the element has
+  ;; the Any type incorrectly
+  (+ 1 (vector-ref (Foo-elems (make-foo 1)) 0)))

collects/typed-racket/rep/free-variance.rkt

@@ -46,7 +46,7 @@
   (match var
    ((== Covariant) #'Covariant)
    ((== Contravariant) #'Contravariant)
-   ((== Invariant) #'Contravariant)
+   ((== Invariant) #'Invariant)
    ((== Constant) #'Constant)
    ((== Dotted) #'Dotted)))