Implement correct scope of for-in expression.

pkg/fasta/test/for_in_scope.dart

Index: pkg/fasta/test/for_in_scope.dart
diff --git a/pkg/fasta/test/for_in_scope.dart b/pkg/fasta/test/for_in_scope.dart
new file mode 100644
index 0000000000000000000000000000000000000000..86fb4cf1444b91ad49158416e1f37f75f4aa8a2f
--- /dev/null
+++ b/pkg/fasta/test/for_in_scope.dart
@@ -0,0 +1,9 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+main(List<String> arguments) {
+  for (String arguments in arguments) {
+    print(arguments);
+  }
+}