Fix TR treatment of parent row in class types

This bug manifested in having extraneous class
members in a type for a class whose superclass
expression was a mixin application.

original commit: c1a27951a38733419702b6647b97f1547ed24ae3

pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/typecheck/check-class-unit.rkt

@@ -1348,7 +1348,12 @@
     (cond [(not init-rest-name) super-init-rest]
           [(dict-ref annotation-table init-rest-name #f)]
           [else (-lst Univ)]))
-  (make-Instance (make-Class super-row init-types field-types
+  (make-Instance (make-Class ;; only inherit parent row if it's a variable
+                             ;; FIXME: fix this when substitution with rows
+                             ;;        is made more sensible
+                             (and (or (F? super-row) (B? super-row))
+                                  super-row)
+                             init-types field-types
                              public-types augment-types init-rest-type)))
 
 ;; function->method : Function Type -> Function

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

@@ -1035,6 +1035,19 @@
                               #:row (make-Row null `([x ,-Integer]) null null #f)
                               #:field ([x -Integer])))
                       -true-filter)]
+   ;; test bad manipulation of rows for inheritance
+   [tc-e (let ()
+           (: c% (Class (init [x String] [y String])))
+           (define c% (class object% (super-new) (init x y)))
+           (: f (All (r #:row) (-> (Class #:row-var r) (Class #:row-var r))))
+           (define (f x) x)
+           ;; should have the same type as c%
+           (define c2% (f c%))
+           (: d% (Class (init [y String])))
+           ;; should be the same as inheriting from c%
+           (define d% (class c2% (super-new [x "foo"])))
+           (void))
+         -Void]
    ;; Check simple use of pubment
    [tc-e (let ()
            (define c%