Improve the event handling for string input stream

tests/standalone/src/StatusFileParserTest.dart

 // Copyright (c) 2011, 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.
 
 #library("StatusFileParserTest");
 
 #import("../../../tools/testing/dart/status_file_parser.dart");
 
 
 void main() {
@@ skipping 10 matching lines @@
   TestReadStatusFile("compiler/tests/dartc/dartc.status");
   TestReadStatusFile("client/tests/client/client.status");
   TestReadStatusFile("client/tests/dartc/dartc.status");
 }
 
 
 void TestReadStatusFile(String filePath) {
   File file = new File(getFilename(filePath));
   if (file.existsSync()) {
     List<Section> sections = new List<Section>();
-    ReadConfigurationInto(filePath, sections);
-    Expect.isTrue(sections.length > 0);
+    ReadConfigurationInto(filePath, sections, () {
+        Expect.isTrue(sections.length > 0);
+      });
   }
 }