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

utils/tests/pub/sdk_constraint_test.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 check_sdk_test;
 
-import '../../../pkg/scheduled_test/lib/scheduled_test.dart';
+import 'package:scheduled_test/scheduled_test.dart';
 
 import 'descriptor.dart' as d;
 import "test_pub.dart";
 
 main() {
   initConfig();
 
   for (var command in ["install", "update"]) {
     var success = new RegExp(r"Dependencies installed!$");
     if (command == "update") {
@@ skipping 119 matching lines @@
             Some packages that were installed are not compatible with your SDK version 0.1.2+3 and may not work:
             - 'myapp' requires >2.0.0
             - 'foo' requires >3.0.0
 
             You may be able to resolve this by upgrading to the latest Dart SDK
             or adding a version constraint to use an older version of a package.
             """);
     });
   }
 }