Update tests for pkg/http for new library

pkg/http/lib/http.dart

Index: pkg/http/lib/http.dart
diff --git a/pkg/http/lib/http.dart b/pkg/http/lib/http.dart
index bb59726cf7380ab04d77b78f0fd7b9f87a874963..618cd77f6592c5a2dd1a3a7a590ac23fdb19fb40 100644
--- a/pkg/http/lib/http.dart
+++ b/pkg/http/lib/http.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2013, 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.
 
@@ -26,7 +26,7 @@
 ///     client.post(
 ///         "http://example.com/whatsit/create",
 ///         fields: {"name": "doodle", "color": "blue"})
-///       .chain((response) => client.get(response.bodyFields['uri']))
+///       .then((response) => client.get(response.bodyFields['uri']))
 ///       .then((response) => print(response.body))
 ///       .onComplete((_) => client.close());
 ///