Add stack chain support to pkg/watcher and pkg/http.

pkg/http/lib/src/base_client.dart

 // Copyright (c) 2012, 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 base_client;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
@@ skipping 110 matching lines @@
   ///
   /// Implementers should call [BaseRequest.finalize] to get the body of the
   /// request as a [ByteStream]. They shouldn't make any assumptions about the
   /// state of the stream; it could have data written to it asynchronously at a
   /// later point, or it could already be closed when it's returned.
   Future<StreamedResponse> send(BaseRequest request);
 
   /// Sends a non-streaming [Request] and returns a non-streaming [Response].
   Future<Response> _sendUnstreamed(String method, url,
       Map<String, String> headers, [body, Encoding encoding]) {
-    return new Future.sync(() {
+    return syncFuture(() {
       if (url is String) url = Uri.parse(url);
       var request = new Request(method, url);
 
       if (headers != null) request.headers.addAll(headers);
       if (encoding != null) request.encoding = encoding;
       if (body != null) {
         if (body is String) {
           request.body = body;
         } else if (body is List) {
           request.bodyBytes = body;
@@ skipping 16 matching lines @@
       message = "$message: ${response.reasonPhrase}";
     }
     throw new HttpException("$message.");
   }
 
   /// Closes the client and cleans up any resources associated with it. It's
   /// important to close each client when it's done being used; failing to do so
   /// can cause the Dart process to hang.
   void close() {}
 }