Add regression test

ahejlsberg · ahejlsberg · commit 80e5f2f314b4 · 2017-01-22T11:53:18.000-08:00
diff --git a/tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts b/tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts
@@ -505,3 +505,15 @@ function updateIds2<T extends { [x: string]: string }, K extends keyof T>(
 // Repro from #13514
 
 declare function head<T extends Array<any>>(list: T): T[0];
+
+// Repro from #13604
+
+class A<T> {
+	props: T & { foo: string };
+}
+
+class B extends A<{ x: number}> {
+	f(p: this["props"]) {
+		p.x;
+	}
+}
