[es6] Ensure that for-in/of loops have a proper TDZ for their boundnames

test/mjsunit/harmony/destructuring.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-destructuring --harmony-computed-property-names
 // Flags: --harmony-arrow-functions
 
 (function TestObjectLiteralPattern() {
   var { x : x, y : y } = { x : 1, y : 2 };
   assertEquals(1, x);
@@ skipping 710 matching lines @@
   assertThrows("'use strict';function f({x,x}){}", SyntaxError);
   assertThrows("'use strict';function f(x, {x}){}", SyntaxError);
   assertThrows("'use strict';var f = (x,x) => {};", SyntaxError);
   assertThrows("'use strict';var f = ({x,x}) => {};", SyntaxError);
   assertThrows("'use strict';var f = (x, {x}) => {};", SyntaxError);
 
   function ok(x) { var x; }; ok();
   assertThrows("function f({x}) { var x; }; f({});", SyntaxError);
   assertThrows("'use strict'; function f({x}) { let x = 0; }; f({});", SyntaxError);
 }());
+
+
+(function TestForInOfTDZ() {
+  assertThrows("'use strict'; let x = {}; for (let [x, y] of {x});", ReferenceError);
+  assertThrows("'use strict'; let x = {}; for (let [y, x] of {x});", ReferenceError);
+  assertThrows("'use strict'; let x = {}; for (let [x, y] in {x});", ReferenceError);
+  assertThrows("'use strict'; let x = {}; for (let [y, x] in {x});", ReferenceError);
+}());