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

mojo/public/dart/third_party/barback/lib/src/transformer/transformer_group.dart

Index: mojo/public/dart/third_party/barback/lib/src/transformer/transformer_group.dart
diff --git a/mojo/public/dart/third_party/barback/lib/src/transformer/transformer_group.dart b/mojo/public/dart/third_party/barback/lib/src/transformer/transformer_group.dart
new file mode 100644
index 0000000000000000000000000000000000000000..17a2e57c03a3e930af4f9af46b7f2bcef3d6ccea
--- /dev/null
+++ b/mojo/public/dart/third_party/barback/lib/src/transformer/transformer_group.dart
@@ -0,0 +1,30 @@
+// 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 barback.transformer.transformer_group;
+
+/// A [TransformerGroup] encapsulates a phased collection of transformers.
+///
+/// A transformer group is defined like a collection of phases, such as you
+/// might pass to [Barback.updateTransformers]. Input assets are transformed by
+/// the first phase, whose results are passed to the second phase, and so on.
+///
+/// However, from the perspective of someone using a [TransformerGroup], it
+/// works just like a [Transformer]. It can be included in phases, and will run
+/// in parallel to other transformers or groups in those phases. Other
+/// transformers and groups will be unable to see any intermediate assets that
+/// are generated by one phase of the group and consumed by another. Phases
+/// after the one containing the group will be able to see its outputs, though.
+class TransformerGroup {
+  /// The phases that comprise this group.
+  ///
+  /// Each element of the inner iterable must be either a [Transformer] or a
+  /// [TransformerGroup].
+  final Iterable<Iterable> phases;
+
+  TransformerGroup(Iterable<Iterable> phases)
+      : this.phases = phases.map((phase) => phase.toList()).toList();
+
+  String toString() => "group of $phases";
+}