"tap" does not fire when dragging before releasing

### Problem description
When touching down a widget, dragging inside the widget area and then releasing the finger inside the widget area, the `"tap"` event is not fired, even when no listeners for `"swipe"` and `"pan"` are registered. One often slides unconsciously before releasing the finger, although a tapping gesture is intended.

### Expected behavior
Since no event listeners for events like `"swipe"` and `"pan"` are registered, even when sliding with the finger before releasing should result into `"tap"` being triggered.

### Environment

- Tabris.js version: 2.0

### Code snippet
See `imageview-as-a-button` snippet.