[strong] Adding regression cases which should always continue working.

test/mjsunit/strong/mutually-recursive-funcs.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --strong-mode
+
+"use strong";
+
+function foo(param, fooCount, barCount) {
+  if (param === 0)
+    return {'foo': fooCount, 'bar': barCount};
+  return bar(param - 1, fooCount + 1, barCount);
+}
+
+function bar(param, fooCount, barCount) {
+  if (param === 0)
+    return {'foo': fooCount, 'bar': barCount};
+  return foo(param - 1, fooCount, barCount + 1);
+}
+
+(function TestMutuallyRecursiveFunctions() {
+  let obj = foo(10, 0, 0);
+  assertEquals(obj.foo, 5);
+  assertEquals(obj.bar, 5);
+})();