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

mojo/public/dart/third_party/matcher/lib/matcher.dart

Index: mojo/public/dart/third_party/matcher/lib/matcher.dart
diff --git a/mojo/public/dart/third_party/matcher/lib/matcher.dart b/mojo/public/dart/third_party/matcher/lib/matcher.dart
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+// Copyright (c) 2014, 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.
+
+/// Support for specifying test expectations, such as for unit tests.
+library matcher;
+
+export 'src/core_matchers.dart';
+export 'src/description.dart';
+export 'src/error_matchers.dart';
+export 'src/interfaces.dart';
+export 'src/iterable_matchers.dart';
+export 'src/map_matchers.dart';
+export 'src/numeric_matchers.dart';
+export 'src/operator_matchers.dart';
+export 'src/string_matchers.dart';
+export 'src/util.dart';