Refactor test servers to make them less global.

test/list_package_dirs/lists_dependency_directories_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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 d.file.
 
 import 'package:path/path.dart' as path;
 import 'package:pub/src/io.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
@@ skipping 16 matching lines @@
     pubGet();
 
     // Note: Using canonicalize here because pub gets the path to the
     // entrypoint package from the working directory, which has had symlinks
     // resolve. On Mac, "/tmp" is actually a symlink to "/private/tmp", so we
     // need to accomodate that.
     schedulePub(args: ["list-package-dirs", "--format=json"],
         outputJson: {
           "packages": {
             "foo": path.join(sandboxDir, "foo", "lib"),
-            "bar": port.then((p) => path.join(sandboxDir, cachePath, "hosted",
-                "localhost%58$p", "bar-1.0.0", "lib")),
+            "bar": globalServer.port.then(
+                (p) => path.join(sandboxDir, cachePath, "hosted",
+                    "localhost%58$p", "bar-1.0.0", "lib")),
             "myapp": canonicalize(path.join(sandboxDir, appPath, "lib"))
           },
           "input_files": [
             canonicalize(path.join(sandboxDir, appPath, "pubspec.lock")),
             canonicalize(path.join(sandboxDir, appPath, "pubspec.yaml"))
           ]
         });
   });
 }