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

utils/pub/entrypoint.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 entrypoint;
 
 import 'dart:async';
 
-import '../../pkg/pathos/lib/path.dart' as path;
+import 'package:pathos/path.dart' as path;
 
 import 'io.dart';
 import 'lock_file.dart';
 import 'log.dart' as log;
 import 'package.dart';
 import 'pubspec.dart';
 import 'sdk.dart' as sdk;
 import 'system_cache.dart';
 import 'utils.dart';
 import 'version.dart';
@@ skipping 286 matching lines @@
       // doesn't matter.
       if (dirExists(symlink)) {
         deleteDir(symlink);
       } else if (fileExists(symlink)) {
         deleteFile(symlink);
       }
       return createSymlink(packagesDir, symlink, relative: true);
     });
   }
 }