Add regression test

ahejlsberg · ahejlsberg · commit f6c79a631cf3 · 2018-01-18T17:28:37.000-08:00
diff --git a/tests/cases/compiler/reverseMappedContravariantInference.ts b/tests/cases/compiler/reverseMappedContravariantInference.ts
@@ -0,0 +1,6 @@
+// @strict: true
+
+// Repro from #21273
+
+declare function conforms<T>(source: { [K in keyof T]: (val: T[K]) => boolean }): (value: T) => boolean;
+conforms({ foo: (v: string) => false })({ foo: "hello" });
