Disable classes in sloppy mode unless --harmony-sloppy is set

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
+// Flags: --harmony-classes --harmony-sloppy
 
 (function TestBasics() {
   var C = class C {}
   assertEquals(typeof C, 'function');
   assertEquals(C.__proto__, Function.prototype);
   assertEquals(Object.prototype, Object.getPrototypeOf(C.prototype));
   assertEquals(Function.prototype, Object.getPrototypeOf(C));
   assertEquals('C', C.name);
 
   class D {}
@@ skipping 745 matching lines @@
   }, ReferenceError);
 
   assertThrows(function() {
     (class x extends x {});
   }, ReferenceError);
 
   assertThrows(function() {
     var x = (class x extends x {});
   }, ReferenceError);
 })();