Make servePackages's contents argument saner.

sdk/lib/_internal/pub/test/snapshot/creates_a_snapshot_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.
 
 library pub_tests;
 
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   initConfig();
   integration("creates a snapshot for an immediate dependency's executables",
       () {
-    servePackages([packageMap("foo", "1.2.3")], contents: [
-      d.dir("bin", [
-        d.file("hello.dart", "void main() => print('hello!');"),
-        d.file("goodbye.dart", "void main() => print('goodbye!');"),
-        d.file("shell.sh", "echo shell"),
-        d.dir("subdir", [
-          d.file("sub.dart", "void main() => print('sub!');")
+    servePackages((builder) {
+      builder.serve("foo", "1.2.3", contents: [
+        d.dir("bin", [
+          d.file("hello.dart", "void main() => print('hello!');"),
+          d.file("goodbye.dart", "void main() => print('goodbye!');"),
+          d.file("shell.sh", "echo shell"),
+          d.dir("subdir", [
+            d.file("sub.dart", "void main() => print('sub!');")
+          ])
         ])
-      ])
-    ]);
+      ]);
+    });
 
     d.appDir({"foo": "1.2.3"}).create();
 
     pubGet(output: allOf([
       contains("Precompiled foo:hello."),
       contains("Precompiled foo:goodbye.")
     ]));
 
     d.dir(p.join(appPath, '.pub', 'bin'), [
       d.file('sdk-version', '0.1.2+3\n'),
       d.dir('foo', [
         d.matcherFile('hello.dart.snapshot', contains('hello!')),
         d.matcherFile('goodbye.dart.snapshot', contains('goodbye!')),
         d.nothing('shell.sh.snapshot'),
         d.nothing('subdir')
       ])
     ]).validate();
 
     var process = pubRun(args: ['foo:hello']);
     process.stdout.expect("hello!");
     process.shouldExit();
 
     process = pubRun(args: ['foo:goodbye']);
     process.stdout.expect("goodbye!");
     process.shouldExit();
   });
 }