Use "package:" imports for pub.

test/global/activate/activate_path_after_hosted_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:path/path.dart' as p;
+import 'package:pub/src/io.dart';
 
-import '../../../lib/src/io.dart';
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
   initConfig();
   integration('activating a hosted package deactivates the path one', () {
     servePackages((builder) {
       builder.serve("foo", "1.0.0", contents: [
         d.dir("bin", [
           d.file("foo.dart", "main(args) => print('hosted');")
@@ skipping 14 matching lines @@
     schedulePub(args: ["global", "activate", "-spath", "../foo"], output: """
         Package foo is currently active at version 1.0.0.
         Activated foo 2.0.0 at path "$path".""");
 
     // Should now run the path one.
     var pub = pubRun(global: true, args: ["foo"]);
     pub.stdout.expect("path");
     pub.shouldExit();
   });
 }