Consider using passive event listeners

When rendering a Downshift component in Chrome, I see this message logged in the console:
```
[Violation] Added non-passive event listener to a scroll-blocking 'touchstart' event. Consider marking event handler as 'passive' to make the page more responsive. See https://www.chromestatus.com/feature/5745543795965952
```

Chrome developer tools indicates that these listeners are not passive:
https://github.com/downshift-js/downshift/blob/master/src/hooks/utils.js#L421-L425

Would it be possible to make these listeners passive without affecting functionality?