Correct and GC unrecognized flags from our tests.

tests/isolate/message_enum_test.dart

 // Copyright (c) 2014, 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
-
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import "dart:isolate";
 
 enum Foo { BAR, BAZ }
 
 main() {
   var p;
   p = new RawReceivePort((map) {
     Expect.equals(1, map.keys.length);
     Expect.equals(42, map.values.first);
     var key = map.keys.first;
     Expect.equals(42, map[key]);
     p.close();
   });
   asyncStart();
   Isolate.spawn(sendIt, p.sendPort).whenComplete(asyncEnd);
 }
 
 void sendIt(port) {
   var map = { Foo.BAR: 42 };
   port.send(map);
 }