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

runtime/observatory/tests/service/get_ports_rpc_test.dart

Index: runtime/observatory/tests/service/get_ports_rpc_test.dart
diff --git a/runtime/observatory/tests/service/get_ports_rpc_test.dart b/runtime/observatory/tests/service/get_ports_rpc_test.dart
index 8205754b0e978e9b2da09a52ff670040f43845fc..1c08a16179a94dcf755e9f91959c237825d15c18 100644
--- a/runtime/observatory/tests/service/get_ports_rpc_test.dart
+++ b/runtime/observatory/tests/service/get_ports_rpc_test.dart
@@ -1,7 +1,7 @@
 // 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
 
 library get_ports_rpc_test;