Consider making certain event handlers passive

[neeharv]

https://stackoverflow.com/questions/37721782/what-are-passive-event-listeners
https://stackoverflow.com/questions/39152877/consider-marking-event-handler-as-passive-to-make-the-page-more-responive

This can be opt in as well. If a swipeable should not impede the normal scroll behaviour of the page (for eg, swiping left / right in a carousel), then it doesn't need to be an active listener