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

pkg/scheduled_test/lib/src/descriptor/file_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 'dart:math' as math;
 import 'dart:utf';
 
-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 descriptor describing a single file.
 class FileDescriptor extends Descriptor {
   /// Whether this descriptor describes a binary file. This is only used when
   /// displaying error messages.
   final bool isBinary;
@@ skipping 72 matching lines @@
         }
       }
     }
 
     return "File '$name' should contain:\n"
         "${prefixLines(expected)}\n"
         "but actually contained:\n"
         "${results.join('\n')}";
   }
 }