[es6] Class extends may not be a generator function

test/mjsunit/harmony/classes.js

 // Copyright 2014 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-classes --harmony-sloppy
 
 (function TestBasics() {
   var C = class C {}
   assertEquals(typeof C, 'function');
   assertEquals(C.__proto__, Function.prototype);
@@ skipping 53 matching lines @@
   assertThrows(function() {
     // Function but its .prototype is not null or a function.
     class C extends Math.abs {}
   }, TypeError);
 
   assertThrows(function() {
     Math.abs.prototype = 42;
     class C extends Math.abs {}
   }, TypeError);
   delete Math.abs.prototype;
+
+  assertThrows(function() {
+    function* g() {}
+    class C extends g {}
+  }, TypeError);
 })();
 
 
 (function TestConstructorProperty() {
   class C {}
   assertEquals(C, C.prototype.constructor);
   var descr = Object.getOwnPropertyDescriptor(C.prototype, 'constructor');
   assertTrue(descr.configurable);
   assertFalse(descr.enumerable);
   assertTrue(descr.writable);
@@ skipping 850 matching lines @@
   testClassRestrictedProperties(ClassWithDefaultConstructor);
   testClassRestrictedProperties(Class);
   testClassRestrictedProperties(DerivedClassWithDefaultConstructor);
   testClassRestrictedProperties(DerivedClass);
   testClassRestrictedProperties(class { method() {} });
   testClassRestrictedProperties(class { constructor() {} method() {} });
   testClassRestrictedProperties(class extends Class { });
   testClassRestrictedProperties(
       class extends Class { constructor() { super(); } });
 })();