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

mojo/public/dart/third_party/collection/lib/src/utils.dart

Index: mojo/public/dart/third_party/collection/lib/src/utils.dart
diff --git a/mojo/public/dart/third_party/collection/lib/src/utils.dart b/mojo/public/dart/third_party/collection/lib/src/utils.dart
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index 0000000000000000000000000000000000000000..c9c753777f07c1c5bd930fa4a3a7e32a5377db0f
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+++ b/mojo/public/dart/third_party/collection/lib/src/utils.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.
+
+library dart.pkg.collection.utils;
+
+/// A pair of values.
+class Pair<E, F> {
+  E first;
+  F last;
+
+  Pair(this.first, this.last);
+}