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

mojo/public/dart/third_party/async/lib/src/delegate/sink.dart

Index: mojo/public/dart/third_party/async/lib/src/delegate/sink.dart
diff --git a/mojo/public/dart/third_party/async/lib/src/delegate/sink.dart b/mojo/public/dart/third_party/async/lib/src/delegate/sink.dart
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index 0000000000000000000000000000000000000000..bb50da33972521ff47578bf255566f0262c683ee
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+// 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.
+
+library async.delegate.sink;
+
+/// Simple delegating wrapper around a [Sink].
+///
+/// Subclasses can override individual methods, or use this to expose only the
+/// [Sink] methods of a subclass.
+class DelegatingSink<T> implements Sink<T> {
+  final Sink _sink;
+
+  /// Create a delegating sink forwarding calls to [sink].
+  DelegatingSink(Sink sink)
+      : _sink = sink;
+
+  void add(T data) {
+    _sink.add(data);
+  }
+
+  void close() {
+    _sink.close();
+  }
+}