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

test/mjsunit/harmony/destructuring.js

Index: test/mjsunit/harmony/destructuring.js
diff --git a/test/mjsunit/harmony/destructuring.js b/test/mjsunit/harmony/destructuring.js
index c57dbafda6dbbd90862b11bd6af10e986e7bc2eb..198d4c025702c6de674bc66edfb8b5b8e82c848c 100644
--- a/test/mjsunit/harmony/destructuring.js
+++ b/test/mjsunit/harmony/destructuring.js
@@ -728,3 +728,11 @@
   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);
+}());