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

test/mjsunit/strong/declaration-after-use.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: --strong-mode --harmony_rest_parameters --harmony_arrow_functions --harmony_classes --harmony_computed-property_names
 
 // Note that it's essential for these tests that the reference is inside dead
 // code (because we already produce ReferenceErrors for run-time unresolved
 // variables and don't want to confuse those with strong mode errors). But the
 // errors should *not* be inside lazy, unexecuted functions, since lazy parsing
@@ skipping 174 matching lines @@
   }
 
   let var5 = 5;
   for (; var5 < 10; ++var5) { }
 
   let arr = [1, 2];
   for (let i of arr) {
     i;
   }
 
-  let var6 = [1, 2];
-  // The second var6 resolves to outside (not to the first var6).
-  for (let var6 of var6) { var6; }
-
   try {
     throw "error";
   } catch (e) {
     e;
   }
 
   function func1() { func1; this; }
   func1();
   func1;
 
@@ skipping 41 matching lines @@
       }
       return new CInner();
     }
   }
   (new COuter()).m().n();
 
   // Making sure the check which is supposed to prevent "object literal inside
   // computed property name references the class name" is not too generic:
   class C14 { m() { let obj = { n() { C14 } }; obj.n(); } }; (new C14()).m();
 })();