Fix dart2js compilation error in previous commit

tests/standalone/io/http_stream_close_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:uri";
 
 main() {
   bool serverOnClosed = false;
@@ skipping 16 matching lines @@
     request.inputStream.onClosed = () {
       response.outputStream.onClosed = () {
         serverOnClosed = true;
         checkDone();
       };
       response.outputStream.writeString("hello!");
       response.outputStream.close();
     };
   };
 
-  var connection = client.postUrl(new Uri.fromString("http://127.0.0.1:${server.port}"));
-  connection.onError = (e) => throw e;
+  var connection = client.postUrl(
+      new Uri.fromString("http://127.0.0.1:${server.port}"));
+  connection.onError = (e) { throw e; };
   connection.onRequest = (request) {
     request.contentLength = "hello!".length;
-    request.outputStream.onError = (e) => throw e;
+    request.outputStream.onError = (e) { throw e; };
     request.outputStream.onClosed = () {
       clientOnClosed = true;
       checkDone();
     };
     request.outputStream.writeString("hello!");
     request.outputStream.close();
   };
   connection.onResponse = (response) {
     response.inputStream.onData = response.inputStream.read;
     response.inputStream.onClosed = () {
       requestOnClosed = true;
       checkDone();
     };
   };
 }