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

runtime/observatory/tests/service/break_on_activation_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
+// VMOptions=--compile_all --error_on_bad_type --error_on_bad_override
 
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 
 genRepeater(value) {
   return () => print(value);
 }
 
 genRepeaterNamed(value) {
@@ skipping 184 matching lines @@
   res = await rootLib.evaluate("testeeDo()");
   expect(res is Instance, isTrue); // Not error.
   expect(breaksHit, equals(4));
 
   await cancelFutureSubscription(subscriptionFuture);
 },
 
 ];
 
 main(args) => runIsolateTests(args, tests, testeeBefore: testeeSetup);