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

pkg/scheduled_test/lib/src/descriptor/directory_descriptor.dart

 // Copyright (c) 2013, 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 descriptor.file;
 
 import 'dart:async';
 import 'dart:io';
 
-import '../../../../../pkg/pathos/lib/path.dart' as path;
+import 'package:pathos/path.dart' as path;
 
 import '../../descriptor.dart';
 import '../../scheduled_test.dart';
 import '../utils.dart';
 
 /// A path builder to ensure that [load] uses POSIX paths.
 final path.Builder _path = new path.Builder(style: path.Style.posix);
 
 /// A descriptor describing a directory containing multiple files.
 class DirectoryDescriptor extends Descriptor {
@@ skipping 100 matching lines @@
 
   _DirectoryValidationError(Iterable errors)
       : errors = errors.map((e) => e.toString()).toList();
 
   String toString() {
     if (errors.length == 1) return errors.single;
     return errors.map((e) => prefixLines(e, prefix: '  ', firstPrefix: '* '))
         .join('\n');
   }
 }