Modified unittest to use new argument syntax.

tests/html/audioelement_test.dart

Index: tests/html/audioelement_test.dart
===================================================================
--- tests/html/audioelement_test.dart	(revision 14156)
+++ tests/html/audioelement_test.dart	(working copy)
@@ -9,13 +9,13 @@
   test('constructorTest1', () {
       var audio = new AudioElement();
       expect(audio, isNotNull);
-      expect(audio is AudioElement);
+      expect(audio is AudioElement, isTrue);
     });
 
   test('constructorTest2', () {
       var audio = new AudioElement('hahaURL');
       expect(audio, isNotNull);
-      expect(audio is AudioElement);
+      expect(audio is AudioElement, isTrue);
       expect(audio.src, contains('hahaURL'));
     });
 }