Switch pkg packages, pub, and dartdoc to use package: imports.

utils/pub/git_source.dart

 // Copyright (c) 2012, 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 git_source;
 
 import 'dart:async';
 
-import '../../pkg/pathos/lib/path.dart' as path;
+import 'package:pathos/path.dart' as path;
 
 import 'git.dart' as git;
 import 'io.dart';
 import 'log.dart' as log;
 import 'package.dart';
 import 'source.dart';
 import 'source_registry.dart';
 import 'utils.dart';
 
 /// A package source that installs packages from Git repos.
@@ skipping 182 matching lines @@
     return description['ref'];
   }
 
   /// Returns [description] if it's a description, or [PackageId.description] if
   /// it's a [PackageId].
   _getDescription(description) {
     if (description is PackageId) return description.description;
     return description;
   }
 }