check parent for variable collisions when remapping closurified block scopes - fixes #915, closes #922

test/fixtures/transformation/es6-block-scoping/wrap-closure-shadow-variables/actual.js

@@ -0,0 +1,5 @@
+let a = 1;
+for (let a = 1; a < 100; a++) {
+  items.forEach(item => a);
+}
+console.log(a);

test/fixtures/transformation/es6-block-scoping/wrap-closure-shadow-variables/expected.js

@@ -0,0 +1,11 @@
+"use strict";
+
+var a = 1;
+for (var _a = 1; _a < 100; _a++) {
+  (function (_a) {
+    items.forEach(function (item) {
+      return _a;
+    });
+  })(_a);
+}
+console.log(a);