Fix updating packages map on reload and add a regression test

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';
 import 'service_test_common.dart';
 import 'package:observatory/service.dart';
 import 'package:path/path.dart' as path;
 import 'package:unittest/unittest.dart';
 
 // Chop off the file name.
 String baseDirectory = path.dirname(Platform.script.path) + '/';
 
 Uri baseUri = Platform.script.replace(path: baseDirectory);
 Uri spawnUri = baseUri.resolveUri(Uri.parse('complex_reload/v1/main.dart'));
 Uri v2Uri = baseUri.resolveUri(Uri.parse('complex_reload/v2/main.dart'));
 Uri v3Uri = baseUri.resolveUri(Uri.parse('complex_reload/v3/main.dart'));
+Uri v2PackagesUri = baseUri.resolveUri(Uri.parse('complex_reload/v2/packages'));
 
 testMain() async {
   print(baseUri);
   debugger(); // Stop here.
   // Spawn the child isolate.
   I.Isolate isolate = await I.Isolate.spawnUri(spawnUri, [], null);
   print(isolate);
   debugger();
 }
 
@@ skipping 24 matching lines @@
         vm.isolates.firstWhere((Isolate i) => i != mainIsolate);
     expect(slaveIsolate, isNotNull);
 
     // 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, 'banana');
+    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);