Add redirect method to HttpResponse

sdk/lib/io/http_impl.dart

Index: sdk/lib/io/http_impl.dart
diff --git a/sdk/lib/io/http_impl.dart b/sdk/lib/io/http_impl.dart
index 3af4000b2f300237c9b4346b3c006f582f1d6408..3cf6cde93bd2900c1d7b2bf5078f362b4f546004 100644
--- a/sdk/lib/io/http_impl.dart
+++ b/sdk/lib/io/http_impl.dart
@@ -708,6 +708,13 @@ class _HttpResponse extends _HttpOutboundMessage<HttpResponse>
     _reasonPhrase = reasonPhrase;
   }
 
+  Future redirect(Uri location, {int status: HttpStatus.MOVED_TEMPORARILY}) {
+    if (_headersWritten) throw new StateError("Header already sent");
+    statusCode = status;
+    headers.set("Location", location.toString());
+    return close();
+  }
+
   Future<Socket> detachSocket() {
     if (_headersWritten) throw new StateError("Headers already sent");
     deadline = null;  // Be sure to stop any deadline.
@@ -1908,7 +1915,7 @@ class _HttpServer extends Stream<HttpRequest> implements HttpServer {
         backlog: backlog,
         requestClientCertificate: requestClientCertificate)
         .then((socket) {
-          return new _HttpServer._(socket, true);
+            return new _HttpServer._(socket, true);
         });
   }