Implement rewind: drop one or more frames from the debugger.

runtime/observatory/tests/service/pause_idle_isolate_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=--error_on_bad_type --error_on_bad_override
 
 import 'dart:developer';
 import 'dart:io';
 import 'dart:isolate' show ReceivePort;
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/service_io.dart';
@@ skipping 34 matching lines @@
   var interruptFuture = hasPausedFor(isolate, ServiceEvent.kPauseInterrupted);
   print('Pausing...');
   await isolate.pause();
   await interruptFuture;
 },
 
 ];
 
 main(args) => runIsolateTests(args, tests,
                               testeeConcurrent: testMain,
-                              trace_service: true,
-                              verbose_vm: true);
+                              verbose_vm: true,
+                              extraArgs: [ '--trace-service',
+                                           '--trace-service-verbose' ]);