Refactor test servers to make them less global.

test/get/cache_transformed_dependency_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:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import '../serve/utils.dart';
 
@@ skipping 185 matching lines @@
           d.file("foo.dart", "final message = 'Hello!';")
         ])
       ]);
 
       builder.serve("bar", "5.6.7");
     });
 
     d.appDir({"foo": "1.2.3"}).create();
     pubGet(output: contains("Precompiled foo."));
 
-    servePackages((builder) => builder.serve("bar", "6.0.0"));
+    globalPackageServer.add((builder) => builder.serve("bar", "6.0.0"));
     pubUpgrade(output: contains("Precompiled foo."));
   });
 
   integration("doesn't recache when an unrelated dependency is updated", () {
     servePackages((builder) {
       builder.serveRealPackage('barback');
 
       builder.serve("foo", "1.2.3",
           deps: {'barback': 'any'},
           pubspec: {'transformers': ['foo']},
           contents: [
         d.dir("lib", [
           d.file("transformer.dart", replaceTransformer("Hello", "Goodbye")),
           d.file("foo.dart", "final message = 'Hello!';")
         ])
       ]);
 
       builder.serve("bar", "5.6.7");
     });
 
     d.appDir({"foo": "1.2.3"}).create();
     pubGet(output: contains("Precompiled foo."));
 
-    servePackages((builder) => builder.serve("bar", "6.0.0"));
+    globalPackageServer.add((builder) => builder.serve("bar", "6.0.0"));
     pubUpgrade(output: isNot(contains("Precompiled foo.")));
   });
 
   integration("caches the dependency in debug mode", () {
     servePackages((builder) {
       builder.serveRealPackage('barback');
 
       builder.serve("foo", "1.2.3",
           deps: {'barback': 'any'},
           pubspec: {'transformers': ['foo']},
@@ skipping 192 matching lines @@
   Future apply(Transform transform) {
     return transform.primaryInput.readAsString().then((contents) {
       transform.addOutput(new Asset.fromString(
           transform.primaryInput.id,
           contents.replaceAll("$input", "$output")));
     });
   }
 }
 """;
 }