Add regression tests

Author: ahejlsberg

tests/cases/compiler/contravariantTypeAliasInference.ts

@@ -0,0 +1,19 @@
+// @strict: true
+
+type Func1<T> = (x: T) => void;
+type Func2<T> = ((x: T) => void) | undefined;
+
+declare let f1: Func1<string>;
+declare let f2: Func1<"a">;
+
+declare function foo<T>(f1: Func1<T>, f2: Func1<T>): void;
+
+foo(f1, f2);
+
+declare let g1: Func2<string>;
+declare let g2: Func2<"a">;
+
+declare function bar<T>(g1: Func2<T>, g2: Func2<T>): void;
+
+bar(f1, f2);
+bar(g1, g2);