[es6] Fix return checking in derived constructors

test/mjsunit/harmony/classes-derived-return-type.js

Index: test/mjsunit/harmony/classes-derived-return-type.js
diff --git a/test/mjsunit/harmony/classes-derived-return-type.js b/test/mjsunit/harmony/classes-derived-return-type.js
new file mode 100644
index 0000000000000000000000000000000000000000..8283bcb2270f13f41f1f3bbabb00c07de69a2766
--- /dev/null
+++ b/test/mjsunit/harmony/classes-derived-return-type.js
@@ -0,0 +1,90 @@
+// 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: --harmony-sloppy
+
+
+class Base {}
+
+class DerivedWithReturn extends Base {
+  constructor(x) {
+    super();
+    return x;
+  }
+}
+
+assertThrows(function() {
+  new DerivedWithReturn(null);
+}, TypeError);
+assertThrows(function() {
+  new DerivedWithReturn(42);
+}, TypeError);
+assertThrows(function() {
+  new DerivedWithReturn(true);
+}, TypeError);
+assertThrows(function() {
+  new DerivedWithReturn('hi');
+}, TypeError);
+assertThrows(function() {
+  new DerivedWithReturn(Symbol());
+}, TypeError);
+
+
+assertInstanceof(new DerivedWithReturn(undefined), DerivedWithReturn);
+function f() {}
+assertInstanceof(new DerivedWithReturn(new f()), f);
+assertInstanceof(new DerivedWithReturn(/re/), RegExp);
+
+
+class DerivedWithReturnNoSuper extends Base {
+  constructor(x) {
+    return x;
+  }
+}
+
+
+assertThrows(function() {
+  new DerivedWithReturnNoSuper(null);
+}, TypeError);
+assertThrows(function() {
+  new DerivedWithReturnNoSuper(42);
+}, TypeError);
+assertThrows(function() {
+  new DerivedWithReturnNoSuper(true);
+}, TypeError);
+assertThrows(function() {
+  new DerivedWithReturnNoSuper('hi');
+}, TypeError);
+assertThrows(function() {
+  new DerivedWithReturnNoSuper(Symbol());
+}, TypeError);
+assertThrows(function() {
+  new DerivedWithReturnNoSuper(undefined);
+}, ReferenceError);
+
+
+function f2() {}
+assertInstanceof(new DerivedWithReturnNoSuper(new f2()), f2);
+assertInstanceof(new DerivedWithReturnNoSuper(/re/), RegExp);
+
+
+class DerivedReturn extends Base {
+  constructor() {
+    super();
+    return;
+  }
+}
+
+assertInstanceof(new DerivedReturn(), DerivedReturn);
+
+
+
+class DerivedReturnThis extends Base {
+  constructor() {
+    super();
+    return this;
+  }
+}
+
+assertInstanceof(new DerivedReturnThis(), DerivedReturnThis);