Buffer the entire http header to one packet, and buffer other data in chunks of 4-16 kb.

tests/standalone/io/http_client_request_test.dart

 // 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.
 
 import "dart:io";
 import "dart:isolate";
 import "dart:scalarlist";
 
 void testClientRequest(void handler(request)) {
   HttpServer.bind().then((server) {
@@ skipping 29 matching lines @@
     });
     return request.response;
   });
 }
 
 void testBadResponseAdd() {
   testClientRequest((request) {
     var port = new ReceivePort();
     request.contentLength = 0;
     request.writeBytes([0]);
+    request.close();
     request.done.catchError((error) {
       port.close();
     }, test: (e) => e is HttpException);
     return request.response;
   });
 
   testClientRequest((request) {
     var port = new ReceivePort();
     request.contentLength = 5;
     request.writeBytes([0, 0, 0]);
     request.writeBytes([0, 0, 0]);
+    request.close();
     request.done.catchError((error) {
       port.close();
     }, test: (e) => e is HttpException);
     return request.response;
   });
 
   testClientRequest((request) {
     var port = new ReceivePort();
     request.contentLength = 0;
     request.writeBytes(new Uint8List(64 * 1024));
     request.writeBytes(new Uint8List(64 * 1024));
     request.writeBytes(new Uint8List(64 * 1024));
+    request.close();
     request.done.catchError((error) {
       port.close();
     }, test: (e) => e is HttpException);
     return request.response;
   });
 }
 
 void testBadResponseClose() {
   testClientRequest((request) {
     var port = new ReceivePort();
@@ skipping 15 matching lines @@
     }, test: (e) => e is HttpException);
     return request.response;
   });
 }
 
 void main() {
   testResponseDone();
   testBadResponseAdd();
   testBadResponseClose();
 }