Merge all http-outgoing transfomers into _HttpOutgoing, including simpler(better) buffering.

tests/standalone/io/http_outgoing_size_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.
+//
+// VMOptions=
+// VMOptions=--short_socket_read
+// VMOptions=--short_socket_write
+// VMOptions=--short_socket_read --short_socket_write
+
+import 'dart:io';
+import 'dart:typed_data';
+
+import 'package:expect/expect.dart';
+
+void testChunkedBufferSizeMsg() {
+  // Buffer of same size as our internal buffer, minus 4. Makes us hit the
+  // boundary.
+  var sendData = new Uint8List(8 * 1024 - 4);
+  for (int i = 0; i < sendData.length; i++) sendData[i] = i % 256;
+
+  HttpServer.bind('127.0.0.1', 0).then((server) {
+    server.listen((request) {
+      // Chunked is on by default. Be sure no data is lost when sending several
+      // chunks of data.
+      request.response.add(sendData);
+      request.response.add(sendData);
+      request.response.add(sendData);
+      request.response.add(sendData);
+      request.response.add(sendData);
+      request.response.add(sendData);
+      request.response.add(sendData);
+      request.response.add(sendData);
+      request.response.close();
+    });
+    var client = new HttpClient();
+    client.get('127.0.0.1', server.port, '/')
+      .then((request) {
+        request.headers.set(HttpHeaders.ACCEPT_ENCODING, "");
+        return request.close();
+      })
+      .then((response) {
+        var buffer = [];
+        response.listen(
+          (data) => buffer.addAll(data),
+          onDone: () {
+            Expect.equals(sendData.length * 8, buffer.length);
+            for (int i = 0; i < buffer.length; i++) {
+              Expect.equals(sendData[i % sendData.length], buffer[i]);
+            }
+            server.close();
+          });
+      });
+  });
+}
+
+
+void main() {
+  testChunkedBufferSizeMsg();
+}