[es6] new.target should not be shadowable in a with scope

test/mjsunit/harmony/new-target.js

 // 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-new-target --harmony-reflect --harmony-destructuring
 // Flags: --harmony-rest-parameters --harmony-arrow-functions
 
 
 (function TestClass() {
   'use strict';
@@ skipping 363 matching lines @@
   function f1() { return eval("'use strict'; new.target") }
   assertSame(f1, new f1);
   function f2() { with ({}) return new.target }
   assertSame(f2, new f2);
   function f3({a}) { return new.target }
   assertSame(f3, new f3({}));
   function f4(...a) { return new.target }
   assertSame(f4, new f4);
   function f5() { 'use strict'; { let x; return new.target } }
   assertSame(f5, new f5);
+  function f6() { with ({'new.target': 42}) return new.target }
+  assertSame(f6, new f6);
 })();