Clean up WheelEvent

tests/html/wheelevent_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.
 
 library wheel_event_test;
+
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_config.dart';
 import 'dart:html';
 
-
 main() {
-
   useHtmlConfiguration();
 
   test('wheelEvent', () {
     var element = new DivElement();
     var eventType = Element.mouseWheelEvent.getEventType(element);
 
     element.onMouseWheel.listen(expectAsync((e) {
       expect(e.screen.x, 100);
       expect(e.deltaX, 0);
       expect(e.deltaY.toDouble(), 240.0);
-      expect(e.deltaMode, isNotNull);
+      expect(e.deltaMode, WheelEvent.DOM_DELTA_PAGE);
     }));
     var event = new WheelEvent(eventType,
-      deltaX: 0,
-      deltaY: 240,
-      screenX: 100);
+        deltaX: 0,
+        deltaY: 240,
+        deltaMode: WheelEvent.DOM_DELTA_PAGE,
+        screenX: 100);
     element.dispatchEvent(event);
   });
 
+  test('wheelEvent with deltaZ', () {
+    var element = new DivElement();
+    var eventType = Element.mouseWheelEvent.getEventType(element);
+
+    element.onMouseWheel.listen(expectAsync((e) {
+      expect(e.deltaX, 0);
+      expect(e.deltaY, 0);
+      expect(e.screen.x, 0);
+      expect(e.deltaZ.toDouble(), 1.0);
+    }));
+    var event = new WheelEvent(eventType, deltaZ: 1.0);
+    element.dispatchEvent(event);
+  });
+
   test('wheelEvent Stream', () {
     var element = new DivElement();
     var eventType = Element.mouseWheelEvent.getEventType(element);
 
     element.onMouseWheel.listen(expectAsync((e) {
       expect(e.screen.x, 100);
-      expect(e.deltaX, 0);
-      expect(e.deltaY.toDouble(), 240.0);
+      expect(e.deltaX.toDouble(), 240.0);
+      expect(e.deltaY, 0);
     }));
-    var event = new WheelEvent(eventType,
-      deltaX: 0,
-      deltaY: 240,
-      screenX: 100);
+    var event = new WheelEvent(eventType, deltaX: 240, deltaY: 0, screenX: 100);
     element.dispatchEvent(event);
   });
 }