Object.getOwnPropertyNames should return string names for indexed properties

test/mjsunit/object-get-own-property-names.js

 // Copyright 2009 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 39 matching lines @@
 assertEquals(2, propertyNames.length);
 assertEquals("a", propertyNames[0]);
 assertEquals("c", propertyNames[1]);
 
 // Check that non-enumerable properties are being returned.
 var propertyNames = Object.getOwnPropertyNames([1, 2]);
 propertyNames.sort();
 assertEquals(3, propertyNames.length);
 assertEquals("0", propertyNames[0]);
 assertEquals("1", propertyNames[1]);
+assertEquals("string", typeof propertyNames[0]);
+assertEquals("string", typeof propertyNames[1]);
 assertEquals("length", propertyNames[2]);
 
 // Check that no proto properties are returned.
 var obj = { foo: "foo" };
 obj.__proto__ = { bar: "bar" };
 propertyNames = Object.getOwnPropertyNames(obj);
 propertyNames.sort();
 assertEquals(1, propertyNames.length);
 assertEquals("foo", propertyNames[0]);
 
@@ skipping 25 matching lines @@
 } catch (e) {
   assertTrue(/on non-object/.test(e));
 }
 
 try {
   Object.getOwnPropertyNames(null);
   assertTrue(false);
 } catch (e) {
   assertTrue(/on non-object/.test(e));
 }