Roll Observatory packages and add a roll script

analyzer/lib/source/package_map_provider.dart

-// 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 source.package_map_provider;
-
-import 'package:analyzer/file_system/file_system.dart';
-
-/**
- * Data structure output by PackageMapProvider.  This contains both the package
- * map and dependency information.
- */
-class PackageMapInfo {
-  /**
-   * The package map itself.  This is a map from package name to a list of
-   * the folders containing source code for the package.
-   *
-   * `null` if an error occurred.
-   */
-  Map<String, List<Folder>> packageMap;
-
-  /**
-   * Dependency information.  This is a set of the paths which were consulted
-   * in order to generate the package map.  If any of these files is
-   * modified, the package map will need to be regenerated.
-   */
-  Set<String> dependencies;
-
-  PackageMapInfo(this.packageMap, this.dependencies);
-}
-
-/**
- * A PackageMapProvider is an entity capable of determining the mapping from
- * package name to source directory for a given folder.
- */
-abstract class PackageMapProvider {
-  /**
-   * Compute a package map for the given folder, if possible.
-   *
-   * If a package map can't be computed (e.g. because an error occurred), a
-   * [PackageMapInfo] will still be returned, but its packageMap will be null.
-   */
-  PackageMapInfo computePackageMap(Folder folder);
-}