Passive event listener

A listener declared with `{ passive: true }`, promising not to call `preventDefault`, which lets the browser start scrolling without waiting to see what the handler does. Without it, every touch and wheel listener adds its own execution time to the delay before the page moves. Browsers now default to passive for touch and wheel listeners on the document, which means a handler that genuinely needs to cancel scrolling has to say `{ passive: false }` explicitly.