Added more (failing) test cases for in typeguard type widening

tests/cases/conformance/controlFlow/controlFlowInOperator.ts

@@ -2,6 +2,8 @@ const a = 'a';
 const b = 'b';
 const d = 'd';
 
+// Type narrowing
+
 type A = { [a]: number; };
 type B = { [b]: string; };
 
@@ -34,3 +36,36 @@ if (d in c) {
 } else {
     c; // (A | B)
 }
+
+// Type widening
+
+declare const e: unknown;
+declare const f: any;
+
+if ('a' in e) {
+    e;      // { a: unknown; }
+    e['a']  // unknown
+} else {
+    e;      // unknown
+}
+
+if ('b' in f) {
+    f;      // { b: unknown; }
+    f['b']  // unknown
+} else {
+    f;      // any
+}
+
+if (a in e) {
+    e;      // { a: unknown; }
+    e[a]  // unknown
+} else {
+    e;      // unknown
+}
+
+if (b in f) {
+    f;      // { b: unknown; }
+    f[b]  // unknown
+} else {
+    f;      // any
+}