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

pkg/scheduled_test/test/substitute_future_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 substitute_future_test;
 
 import 'dart:async';
 
-import '../lib/src/substitute_future.dart';
-import '../../../pkg/unittest/lib/unittest.dart';
+import 'package:scheduled_test/src/substitute_future.dart';
+import 'package:unittest/unittest.dart';
 
 void main() {
   group('with no substitution, works like a normal Future for', () {
     var completer;
     var future;
 
     setUp(() {
       completer = new Completer();
       future = new SubstituteFuture(completer.future);
     });
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   });
 
   test('substituting after a future has completed is an error', () {
     var completer = new Completer();
     var future = new SubstituteFuture(completer.future);
     completer.complete('success');
     expect(() => future.substitute(new Future.immediate(null)),
         throwsStateError);
   });
 }