Use "package:" imports for pub.

test/global/binstubs/outdated_snapshot_test.dart

 // Copyright (c) 2014, 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.
 
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
+import 'package:pub/src/io.dart';
 import 'package:scheduled_test/scheduled_process.dart';
 import 'package:scheduled_test/scheduled_stream.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 
-import '../../../lib/src/io.dart';
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 import 'utils.dart';
 
 main() {
   initConfig();
   integration("a binstub runs 'pub global run' for an outdated snapshot", () {
     servePackages((builder) {
       builder.serve("foo", "1.0.0", pubspec: {
         "executables": {
@@ skipping 26 matching lines @@
     process.shouldExit();
 
     d.dir(cachePath, [
       d.dir('global_packages/foo/bin', [
         d.binaryMatcherFile('script.dart.snapshot', isNot(equals(
             readBinaryFile(testAssetPath('out-of-date.snapshot')))))
       ])
     ]).validate();
   });
 }