Dump some state when complex_reload_test fails

runtime/observatory/tests/service/complex_reload_test.dart

 // Copyright (c) 2016, 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 'test_helper.dart';
 import 'dart:async';
 import 'dart:developer';
 import 'dart:isolate' as I;
 import 'dart:io';
@@ skipping 49 matching lines @@
 
     // Invoke test in v1.
     String v1 = await invokeTest(slaveIsolate);
     expect(v1, 'apple');
 
     // Reload to v2.
     var response = await slaveIsolate.reloadSources(
       rootLibUri: v2Uri.toString(),
       packagesUri: v2PackagesUri.toString(),
     );
+    print(response);
     expect(response['success'], isTrue);
 
     // Invoke test in v2.
     String v2 = await invokeTest(slaveIsolate);
     expect(v2, 'fooLib');
 
     // Reload to v3.
     response = await slaveIsolate.reloadSources(
       rootLibUri: v3Uri.toString(),
     );
     expect(response['success'], isTrue);
 
     // Invoke test in v3.
     String v3 = await invokeTest(slaveIsolate);
     expect(v3, 'cabbage');
   }
 ];
 
 main(args) => runIsolateTests(args, tests, testeeConcurrent: testMain);