Correct and GC unrecognized flags from our tests.

tests/language/enum_index_test.dart

 // Copyright (c) 2015, 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.
 
-// SharedOptions=--enable-enum
-
 // Test index access for enums.
 
 library enum_index_test;
 
 import 'package:expect/expect.dart';
 
 enum Enum {
   A,
   B,
 }
 
 class Class {
   var index;
 }
 
 main() {
   test(null, new Class());
   test(0, Enum.A);
   test(1, Enum.B);
 }
 
 test(expected, object) {
   Expect.equals(expected, object.index);
 }