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

mojo/public/dart/third_party/package_config/lib/src/packages_io_impl.dart

Index: mojo/public/dart/third_party/package_config/lib/src/packages_io_impl.dart
diff --git a/mojo/public/dart/third_party/package_config/lib/src/packages_io_impl.dart b/mojo/public/dart/third_party/package_config/lib/src/packages_io_impl.dart
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index 0000000000000000000000000000000000000000..21b61fdab0591cc483d1af2d53cee5515f659d90
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+++ b/mojo/public/dart/third_party/package_config/lib/src/packages_io_impl.dart
@@ -0,0 +1,37 @@
+// 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.
+
+/// Implementations of [Packages] that can only be used in server based
+/// applications.
+library package_config.packages_io_impl;
+
+import "dart:collection" show UnmodifiableMapView;
+import "dart:io" show Directory;
+import "package:path/path.dart" as path;
+import "packages_impl.dart";
+
+/// A [Packages] implementation based on a local directory.
+class FilePackagesDirectoryPackages extends PackagesBase {
+  final Directory _packageDir;
+  FilePackagesDirectoryPackages(this._packageDir);
+
+  Uri getBase(String packageName) =>
+    new Uri.file(path.join(_packageDir.path, packageName, '.'));
+
+  Iterable<String> _listPackageNames() {
+    return _packageDir.listSync()
+    .where((e) => e is Directory)
+    .map((e) => path.basename(e.path));
+  }
+
+  Iterable<String> get packages => _listPackageNames();
+
+  Map<String, Uri> asMap() {
+    var result = <String, Uri>{};
+    for (var packageName in _listPackageNames()) {
+      result[packageName] = getBase(packageName);
+    }
+    return new UnmodifiableMapView<String, Uri>(result);
+  }
+}