Refactor test servers to make them less global.

test/cache/repair/reinstalls_hosted_packages_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 '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
   integration('reinstalls previously cached hosted packages', () {
     servePackages((builder) {
       builder.serve("foo", "1.2.3");
       builder.serve("foo", "1.2.4");
       builder.serve("foo", "1.2.5");
       builder.serve("bar", "1.2.3");
       builder.serve("bar", "1.2.4");
     });
 
     // Set up a cache with some broken packages.
     d.dir(cachePath, [
       d.dir('hosted', [
-        d.async(port.then((p) => d.dir('localhost%58$p', [
+        d.async(globalServer.port.then((p) => d.dir('localhost%58$p', [
           d.dir("foo-1.2.3", [
             d.libPubspec("foo", "1.2.3"),
             d.file("broken.txt")
           ]),
           d.dir("foo-1.2.5", [
             d.libPubspec("foo", "1.2.5"),
             d.file("broken.txt")
           ]),
           d.dir("bar-1.2.4", [
             d.libPubspec("bar", "1.2.4"),
@@ skipping 12 matching lines @@
           Reinstalled 3 packages.''');
 
     // The broken versions should have been replaced.
     d.hostedCache([
       d.dir("bar-1.2.4", [d.nothing("broken.txt")]),
       d.dir("foo-1.2.3", [d.nothing("broken.txt")]),
       d.dir("foo-1.2.5", [d.nothing("broken.txt")])
     ]).validate();
   });
 }