highlightOnTouch is shown even when button on top is tapped

### Problem description

Creating a `Composite` with `highlightOnTouch` enabled and containing a `Button` leads to unexpected touch feedback. Tapping on the button activates the `highlightOnTouch` feedback of the underlying `Composite`.

### Expected behavior

The `Button` should consume to touch event and the underlying `Composite` should not show any touch feedback.

### Environment

- Tabris.js version: 2.0.0
- Device: iPad Pro 9.5"
- OS: 10.3.3

### Code snippet

```javascript
const {Composite, Button, ui} = require('tabris');

const composite = new Composite({
left: 16, top: '16', right: '16', bottom: '16',
highlightOnTouch: true,
background: 'green'
}).appendTo(ui.contentView);

new Button({
centerX: 0, centerY: 0,
text: 'Button'
}).appendTo(composite);
```