Cleanup: Add more conversion helpers for usage.

Source/modules/device_orientation/NewDeviceOrientationController.cpp

Index: Source/modules/device_orientation/NewDeviceOrientationController.cpp
diff --git a/Source/modules/device_orientation/NewDeviceOrientationController.cpp b/Source/modules/device_orientation/NewDeviceOrientationController.cpp
index 904202e029254ab74828f89e089c59cc8c2dddee..174508b0f15e28359f8c45166be82e16009939ad 100644
--- a/Source/modules/device_orientation/NewDeviceOrientationController.cpp
+++ b/Source/modules/device_orientation/NewDeviceOrientationController.cpp
@@ -89,8 +89,7 @@ void NewDeviceOrientationController::unregisterWithDispatcher()
 
 bool NewDeviceOrientationController::isNullEvent(Event* event)
 {
-    ASSERT(event->type() == EventNames::deviceorientation);
-    DeviceOrientationEvent* orientationEvent = static_cast<DeviceOrientationEvent*>(event);
+    DeviceOrientationEvent* orientationEvent = toDeviceOrientationEvent(event);
     return !orientationEvent->orientation()->canProvideEventData();
 }