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

utils/pub/validator/lib.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 lib_validator;
 
 import 'dart:async';
 import 'dart:io';
 
-import '../../../pkg/pathos/lib/path.dart' as path;
+import 'package:pathos/path.dart' as path;
 
 import '../entrypoint.dart';
 import '../io.dart';
 import '../system_cache.dart';
 import '../utils.dart';
 import '../validator.dart';
 
 // TODO(nweiz): When issue 7196 is fixed, complain about non-Dart files in lib.
 /// A validator that checks that libraries in "lib/" (and not "lib/src/") exist
 /// and are well-formed.
@@ skipping 18 matching lines @@
               "Without that, users cannot import any code from your package.");
         } else if (files.length == 1 && files.first == "src") {
           errors.add('The "lib" directory must contain something other than '
               '"src".\n'
               "Otherwise, users cannot import any code from your package.");
         }
       });
     });
   }
 }