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

pkg/scheduled_test/lib/scheduled_test.dart

Index: pkg/scheduled_test/lib/scheduled_test.dart
diff --git a/pkg/scheduled_test/lib/scheduled_test.dart b/pkg/scheduled_test/lib/scheduled_test.dart
index 8451e18495b7bda3d291e04ce22c6cdc8687069a..4c4eed142d3e0af33f1f75f3ca52e8c6167ee3dd 100644
--- a/pkg/scheduled_test/lib/scheduled_test.dart
+++ b/pkg/scheduled_test/lib/scheduled_test.dart
@@ -175,14 +175,14 @@ library scheduled_test;
 
 import 'dart:async';
 
-import '../../../pkg/unittest/lib/unittest.dart' as unittest;
+import 'package:unittest/unittest.dart' as unittest;
 
 import 'src/schedule.dart';
 import 'src/schedule_error.dart';
 import 'src/utils.dart';
 
-export '../../../pkg/unittest/lib/matcher.dart' hide completes, completion;
-export '../../../pkg/unittest/lib/unittest.dart' show
+export 'package:unittest/matcher.dart' hide completes, completion;
+export 'package:unittest/unittest.dart' show
     config, configure, Configuration, logMessage, expectThrow;
 
 export 'src/schedule.dart';