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

mojo/public/dart/third_party/watcher/lib/watcher.dart

Index: mojo/public/dart/third_party/watcher/lib/watcher.dart
diff --git a/mojo/public/dart/third_party/watcher/lib/watcher.dart b/mojo/public/dart/third_party/watcher/lib/watcher.dart
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+// 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;
+
+import 'dart:async';
+import 'dart:io';
+
+import 'src/watch_event.dart';
+import 'src/directory_watcher.dart';
+import 'src/file_watcher.dart';
+
+export 'src/watch_event.dart';
+export 'src/directory_watcher.dart';
+export 'src/directory_watcher/polling.dart';
+export 'src/file_watcher.dart';
+export 'src/file_watcher/polling.dart';
+
+abstract class Watcher {
+  /// The path to the file or directory whose contents are being monitored.
+  String get path;
+
+  /// The broadcast [Stream] of events that have occurred to the watched file or
+  /// files in the watched directory.
+  ///
+  /// Changes will only be monitored while this stream has subscribers. Any
+  /// changes that occur during periods when there are no subscribers will not
+  /// be reported the next time a subscriber is added.
+  Stream<WatchEvent> get events;
+
+  /// Whether the watcher is initialized and watching for changes.
+  ///
+  /// This is true if and only if [ready] is complete.
+  bool get isReady;
+
+  /// A [Future] that completes when the watcher is initialized and watching for
+  /// changes.
+  ///
+  /// If the watcher is not currently monitoring the file or directory (because
+  /// there are no subscribers to [events]), this returns a future that isn't
+  /// complete yet. It will complete when a subscriber starts listening and the
+  /// watcher finishes any initialization work it needs to do.
+  ///
+  /// If the watcher is already monitoring, this returns an already complete
+  /// future.
+  Future get ready;
+
+  /// Creates a new [DirectoryWatcher] or [FileWatcher] monitoring [path],
+  /// depending on whether it's a file or directory.
+  ///
+  /// If a native watcher is available for this platform, this will use it.
+  /// Otherwise, it will fall back to a polling watcher. Notably, watching
+  /// individual files is not natively supported on Windows, although watching
+  /// directories is.
+  ///
+  /// If [pollingDelay] is passed, it specifies the amount of time the watcher
+  /// will pause between successive polls of the contents of [path]. Making this
+  /// shorter will give more immediate feedback at the expense of doing more IO
+  /// and higher CPU usage. Defaults to one second. Ignored for non-polling
+  /// watchers.
+  factory Watcher(String path, {Duration pollingDelay}) {
+    if (new File(path).existsSync()) {
+      return new FileWatcher(path, pollingDelay: pollingDelay);
+    } else {
+      return new DirectoryWatcher(path, pollingDelay: pollingDelay);
+    }
+  }
+}