Make isEmpty a getter.

runtime/tests/vm/dart/isolate_mirror_local_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.
 //
 // Dart test program for checking implemention of MirrorSystem when
 // inspecting the current isolate.
 //
 // VMOptions=--enable_type_checks
 
 #library('isolate_mirror_local_test');
 
 #import('dart:isolate');
 #import('dart:mirrors');
 
 ReceivePort exit_port;
 Set expectedTests;
 
 void testDone(String test) {
   if (!expectedTests.contains(test)) {
     throw "Unexpected test name '$test'";
   }
   expectedTests.remove(test);
-  if (expectedTests.isEmpty()) {
+  if (expectedTests.isEmpty) {
     // All tests are done.
     exit_port.close();
   }
 }
 
 int global_var = 0;
 final int final_global_var = 0;
 
 // Top-level getter and setter.
 int get myVar { return 5; }
@@ skipping 499 matching lines @@
   // Test that an isolate can reflect on itself.
   mirrorSystemOf(exit_port.toSendPort()).then(testMirrorSystem);
 
   testIntegerInstanceMirror(reflect(1001));
   testStringInstanceMirror(reflect('This\nis\na\nString'));
   testBoolInstanceMirror(reflect(true));
   testNullInstanceMirror(reflect(null));
   testCustomInstanceMirror(reflect(new MyClass(17)));
   testMirrorErrors(currentMirrorSystem());
 }