Upgrade pub to work with crypto 1.0.0 or later.

test/global/activate/activate_hosted_after_git_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 'package:pub/src/io.dart';
-
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
   integration('activating a hosted package deactivates the Git one', () {
     servePackages((builder) {
       builder.serve("foo", "2.0.0", contents: [
         d.dir("bin", [
           d.file("foo.dart", "main(args) => print('hosted');")
         ])
@@ skipping 18 matching lines @@
         Loading source assets...
         Precompiled foo:foo.
         Activated foo 2.0.0.""");
 
     // Should now run the hosted one.
     var pub = pubRun(global: true, args: ["foo"]);
     pub.stdout.expect("hosted");
     pub.shouldExit();
   });
 }