Make isEmpty a getter.

tests/standalone/io/test_runner_test.dart

 // Copyright (c) 2012, 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:isolate");
 #import("../../../tools/testing/dart/test_runner.dart");
 #import("../../../tools/testing/dart/status_file_parser.dart");
 #import("../../../tools/testing/dart/test_options.dart");
 #source("process_test_util.dart");
@@ skipping 57 matching lines @@
   // expectation SKIP is run.  The RunningProcess constructor must throw
   // the exception synchronously, for it to be caught here at the call site.
   Expect.throws(new RunningProcess(MakeTestCase("pass", [SKIP])).start);
 }
 
 void main() {
   // Run the test_runner_test if there are no command-line options.
   // Otherwise, run one of the component tests that always pass,
   // fail, or timeout.
   var arguments = new Options().arguments;
-  if (arguments.isEmpty()) {
+  if (arguments.isEmpty) {
     testTestRunner();
   } else {
     switch (arguments[0]) {
       case 'pass':
         return;
       case 'fail':
         Expect.fail("This test always fails, to test the test scripts.");
         break;
       case 'timeout':
         // Run for 10 seconds, then exit.  This tests a 2 second timeout.
         new Timer(10 * 1000, (t){ });
         break;
       default:
         throw "Unknown option ${arguments[0]} passed to test_runner_test";
     }
   }
 }