Add writeHeaders argument to HttpResponse::detachSocket.

tests/standalone/io/http_detach_socket_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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 import "package:expect/expect.dart";
@@ skipping 30 matching lines @@
                         "content-length: 0\r\n"
                         "\r\n"
                         "Test!",
                         body.toString());
           socket.close();
         });
     });
   });
 }
 
+void testServerDetachSocketNoWriteHeaders() {
+  HttpServer.bind("127.0.0.1", 0).then((server) {
+    server.listen((request) {
+      var response = request.response;
+      response.contentLength = 0;
+      response.detachSocket(writeHeaders: false).then((socket) {
+        Expect.isNotNull(socket);
+        var body = new StringBuffer();
+        socket.listen(
+          (data) => body.write(new String.fromCharCodes(data)),
+          onDone: () => Expect.equals("Some data", body.toString()));
+        socket.write("Test!");
+        socket.close();
+      });
+      server.close();
+    });
+
+    Socket.connect("127.0.0.1", server.port).then((socket) {
+      socket.write("GET / HTTP/1.1\r\n"
+                   "content-length: 0\r\n\r\n"
+                   "Some data");
+      var body = new StringBuffer();
+      socket.listen(
+        (data) => body.write(new String.fromCharCodes(data)),
+        onDone: () {
+          Expect.equals("Test!",body.toString());
+          socket.close();
+        });
+    });
+  });
+}
+
 void testBadServerDetachSocket() {
   HttpServer.bind("127.0.0.1", 0).then((server) {
     server.listen((request) {
       var response = request.response;
       response.contentLength = 0;
       response.close();
       Expect.throws(response.detachSocket);
       server.close();
     });
 
@@ skipping 47 matching lines @@
             });
           socket.write("Some data");
           socket.close();
         });
       });
   });
 }
 
 void main() {
   testServerDetachSocket();
+  testServerDetachSocketNoWriteHeaders();
   testBadServerDetachSocket();
   testClientDetachSocket();
 }