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

mojo/public/dart/third_party/package_config/lib/packages.dart

Index: mojo/public/dart/third_party/package_config/lib/packages.dart
diff --git a/mojo/public/dart/third_party/package_config/lib/packages.dart b/mojo/public/dart/third_party/package_config/lib/packages.dart
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+// 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.
+
+library package_config.packages;
+
+import "src/packages_impl.dart";
+
+/// A package resolution strategy.
+///
+/// Allows converting a `package:` URI to a different kind of URI.
+///
+/// May also allow listing the available packages and converting
+/// to a `Map<String, Uri>` that gives the base location of each available
+/// package. In some cases there is no way to find the available packages,
+/// in which case [packages] and [asMap] will throw if used.
+/// One such case is if the packages are resolved relative to a
+/// `packages/` directory available over HTTP.
+abstract class Packages {
+
+  /// A [Packages] resolver containing no packages.
+  ///
+  /// This constant object is returned by [find] above if no
+  /// package resolution strategy is found.
+  static const Packages noPackages = const NoPackages();
+
+  /// Resolve a package URI into a non-package URI.
+  ///
+  /// Translates a `package:` URI, according to the package resolution
+  /// strategy, into a URI that can be loaded.
+  /// By default, only `file`, `http` and `https` URIs are returned.
+  /// Custom `Packages` objects may return other URIs.
+  ///
+  /// If resolution fails because a package with the requested package name
+  /// is not available, the [notFound] function is called.
+  /// If no `notFound` function is provided, it defaults to throwing an error.
+  ///
+  /// The [packageUri] must be a valid package URI.
+  Uri resolve(Uri packageUri, {Uri notFound(Uri packageUri)});
+
+  /// Return the names of the available packages.
+  ///
+  /// Returns an iterable that allows iterating the names of available packages.
+  ///
+  /// Some `Packages` objects are unable to find the package names,
+  /// and getting `packages` from such a `Packages` object will throw.
+  Iterable<String> get packages;
+
+  /// Return the names-to-base-URI mapping of the available packages.
+  ///
+  /// Returns a map from package name to a base URI.
+  /// The [resolve] method will resolve a package URI with a specific package
+  /// name to a path extending the base URI that this map gives for that
+  /// package name.
+  ///
+  /// Some `Packages` objects are unable to find the package names,
+  /// and calling `asMap` on such a `Packages` object will throw.
+  Map<String, Uri> asMap();
+}