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

pkg/scheduled_test/test/scheduled_test_test.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 scheduled_test_test;
 
 import 'dart:async';
 
-import '../lib/scheduled_test.dart';
-import '../lib/src/mock_clock.dart' as mock_clock;
+import 'package:scheduled_test/scheduled_test.dart';
+import 'package:scheduled_test/src/mock_clock.dart' as mock_clock;
 
 import 'metatest.dart';
 import 'utils.dart';
 
 void main() {
   expectTestsPass('a scheduled test with a correct synchronous expectation '
       'should pass', () {
     test('test', () {
       expect('foo', equals('foo'));
     });
@@ skipping 1411 matching lines @@
   expectTestsFail("aborting the schedule after an out-of-band error should "
       "still surface the error", () {
     test('test', () {
       schedule(() {
         currentSchedule.signalError('error');
         currentSchedule.abort();
       });
     });
   });
 }