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

mojo/public/dart/third_party/path/lib/src/characters.dart

Index: mojo/public/dart/third_party/path/lib/src/characters.dart
diff --git a/mojo/public/dart/third_party/path/lib/src/characters.dart b/mojo/public/dart/third_party/path/lib/src/characters.dart
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index 0000000000000000000000000000000000000000..ff196a6722596dec232eba9976a5b151999e42d2
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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.
+
+/// This library contains character-code definitions.
+library path.characters;
+
+const PLUS = 0x2b;
+const MINUS = 0x2d;
+const PERIOD = 0x2e;
+const SLASH = 0x2f;
+const ZERO = 0x30;
+const NINE = 0x39;
+const COLON = 0x3a;
+const UPPER_A = 0x41;
+const UPPER_Z = 0x5a;
+const LOWER_A = 0x61;
+const LOWER_Z = 0x7a;
+const BACKSLASH = 0x5c;