Correct property descriptors on GeneratorPrototype

test/mjsunit/es6/generators-runtime.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 81 matching lines @@
 
   var expected_property_names = ["next", "throw", "constructor"];
   var found_property_names =
       Object.getOwnPropertyNames(GeneratorObjectPrototype);
 
   expected_property_names.sort();
   found_property_names.sort();
 
   assertArrayEquals(expected_property_names, found_property_names);
 
-  iterator_desc = Object.getOwnPropertyDescriptor(GeneratorObjectPrototype,
+  var constructor_desc = Object.getOwnPropertyDescriptor(
+      GeneratorObjectPrototype, "constructor");
+  assertTrue(constructor_desc !== undefined);
+  assertFalse(constructor_desc.writable);
+  assertFalse(constructor_desc.enumerable);
+  assertTrue(constructor_desc.configurable);
+
+  var next_desc = Object.getOwnPropertyDescriptor(GeneratorObjectPrototype,
+      "next");
+  assertTrue(next_desc !== undefined);
+  assertTrue(next_desc.writable);
+  assertFalse(next_desc.enumerable);
+  assertTrue(next_desc.configurable);
+
+  var throw_desc = Object.getOwnPropertyDescriptor(GeneratorObjectPrototype,
+      "throw");
+  assertTrue(next_desc !== undefined);
+  assertTrue(next_desc.writable);
+  assertFalse(next_desc.enumerable);
+  assertTrue(next_desc.configurable);
+
+  var iterator_desc = Object.getOwnPropertyDescriptor(GeneratorObjectPrototype,
       Symbol.iterator);
   assertTrue(iterator_desc !== undefined);
   assertFalse(iterator_desc.writable);
   assertFalse(iterator_desc.enumerable);
   assertFalse(iterator_desc.configurable);
 
   // The generator object's "iterator" function is just the identity.
   assertSame(iterator_desc.value.call(42), 42);
 }
 TestGeneratorObjectPrototype();
@@ skipping 24 matching lines @@
   assertTrue((function*(){}).prototype !== (function*(){}).prototype);
   assertTrue((function*(){}).prototype !== g.prototype);
   assertTrue(g.prototype instanceof GeneratorFunctionPrototype);
   assertSame(GeneratorObjectPrototype, Object.getPrototypeOf(g.prototype));
   assertTrue(!(g.prototype instanceof Function));
   assertSame(typeof (g.prototype), "object");
 
   assertArrayEquals([], Object.getOwnPropertyNames(g.prototype));
 }
 TestPerGeneratorPrototype();