Stop running pub get at gclient sync time and fix build bugs

mojo/public/dart/third_party/watcher/test/file_watcher/polling_test.dart

Index: mojo/public/dart/third_party/watcher/test/file_watcher/polling_test.dart
diff --git a/mojo/public/dart/third_party/watcher/test/file_watcher/polling_test.dart b/mojo/public/dart/third_party/watcher/test/file_watcher/polling_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..e5025447f08528620f8ac95fba9036ea36186914
--- /dev/null
+++ b/mojo/public/dart/third_party/watcher/test/file_watcher/polling_test.dart
@@ -0,0 +1,23 @@
+// 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.
+
+@TestOn('linux || mac-os')
+
+import 'package:scheduled_test/scheduled_test.dart';
+import 'package:watcher/watcher.dart';
+
+import 'shared.dart';
+import '../utils.dart';
+
+void main() {
+  watcherFactory = (file) => new PollingFileWatcher(file,
+      pollingDelay: new Duration(milliseconds: 100));
+
+  setUp(() {
+    createSandbox();
+    writeFile("file.txt");
+  });
+
+  sharedTests();
+}