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

mojo/public/dart/third_party/watcher/lib/src/watch_event.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.
+
+library watcher.watch_event;
+
+/// An event describing a single change to the file system.
+class WatchEvent {
+  /// The manner in which the file at [path] has changed.
+  final ChangeType type;
+
+  /// The path of the file that changed.
+  final String path;
+
+  WatchEvent(this.type, this.path);
+
+  String toString() => "$type $path";
+}
+
+/// Enum for what kind of change has happened to a file.
+class ChangeType {
+  /// A new file has been added.
+  static const ADD = const ChangeType("add");
+
+  /// A file has been removed.
+  static const REMOVE = const ChangeType("remove");
+
+  /// The contents of a file have changed.
+  static const MODIFY = const ChangeType("modify");
+
+  final String _name;
+  const ChangeType(this._name);
+
+  String toString() => _name;
+}