Fix --compile_all flag (--compile-all is wrong)

runtime/observatory/tests/service/async_generator_breakpoint_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.
-// VMOptions=--compile-all --error_on_bad_type --error_on_bad_override --verbose-debug
+// VMOptions=--compile_all --error_on_bad_type --error_on_bad_override --verbose-debug
 
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 
 printSync() {  // Line 10
   print('sync');
 }
 printAsync() async {  // Line 13
   print('async');
@@ skipping 65 matching lines @@
       if (hits.length == 5) break;
     }
   }
 
   expect(hits, equals([bp1, bp5, bp4, bp2, bp3]));
 }
 
 var tests = [testAsync];
 
 main(args) => runIsolateTests(args, tests, testeeConcurrent: testeeDo);