Use a re-usable buffer for writing HTTP headers. This includes a new header limit of 8192 bytes.

tests/standalone/io/http_server_response_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 256 matching lines @@
                   .fold(0, (s, b) => s + b.length)
                   .then((bytes) {
                     Expect.equals(8, bytes);
                     server.close();
                   });
             });
       });
 }
 
 
+void testBadHeaders() {
+  testServerRequest((server, request) {
+    var value = "a";
+    for (int i = 0; i < 8 * 1024; i++) {
+      value += 'a';
+    }
+    request.response.headers.set('name', value);
+    request.response.close().catchError((error) {
+      server.close();
+    }, test: (e) => e is HttpException);
+  });
+}
+
+
 void main() {
   testResponseDone();
   testResponseAddStream();
   testResponseAddStreamClosed();
   testResponseAddClosed();
   testBadResponseAdd();
   testBadResponseClose();
   testIgnoreRequestData();
+  testBadHeaders();
 }