Fix debugging of async code

tests/standalone/debugger/breakpoint_resolved_test.dart

 // Copyright (c) 2013, 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.
 
 import "debug_lib.dart";
 
 main(List<String> arguments) {
   if (RunScript(testScript, arguments)) return;
 
   bar();
@@ skipping 10 matching lines @@
 var testScript = [
   MatchFrame(0, "main"),
   SetBreakpoint(10),
   SetBreakpoint(12),
   SetBreakpoint(16),
   Resume(),
   MatchFrame(0, "main"),
   Resume(),  // Next breakpoint expected in main, when bar() returns.
   MatchFrame(0, "main"),
   // Only two breakpoint resolved events expected.
-  ExpectEvent("breakpointResolved", {"breakpointId": 1}),
   ExpectEvent("breakpointResolved", {"breakpointId": 2}),
+  ExpectEvent("breakpointResolved", {"breakpointId": 3}),
   Resume(),
 ];