Roll Observatory packages and add a roll script

packages/initialize/test/initializer_parts_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.
+@initializeTracker
+library initialize.initializer_parts_test;
+
+import 'package:initialize/src/initialize_tracker.dart';
+import 'package:initialize/initialize.dart';
+import 'package:unittest/unittest.dart';
+import 'package:unittest/compact_vm_config.dart';
+
+part 'parts/foo.dart';
+part 'parts/bar.dart';
+
+main() {
+  useCompactVMConfiguration();
+
+  // Run all initializers.
+  run().then((_) {
+    test('parts', () {
+      var expectedNames = [
+        const LibraryIdentifier(#initialize.initializer_parts_test, null,
+            'initializer_parts_test.dart'),
+        bar2,
+        bar,
+        foo,
+        baz,
+        Bar2,
+        Bar,
+        Foo,
+        Baz,
+      ];
+      expect(InitializeTracker.seen, expectedNames);
+    });
+  });
+}
+
+@initializeTracker
+class Baz {}
+
+@initializeTracker
+baz() {}