fix forOf scope declarations not propagating to new for loop - fixes #538

lib/6to5/transformation/transformers/es6-for-of.js

@@ -30,6 +30,9 @@ exports.ForOfStatement = function (node, parent, scope, context, file) {
   // push the rest of the original loop body onto our new body
   block.body = block.body.concat(node.body.body);
 
+  // todo: find out why this is necessary? #538
+  loop._scopeInfo = node._scopeInfo;
+
   return loop;
 };