Prevent wheel scroll propagation to parent scroll panels.

trap-scroller.js

function TrapScroller(scroller) {
    function callback(ev) {
        ev.stopPropagation();
        var d = ev.deltaY || 0;
        if (
            (scroller.scrollHeight !== scroller.offsetHeight) && (
            (d < 0 && scroller.scrollTop === 0) ||
            (d > 0 && (scroller.scrollTop >= scroller.scrollHeight - scroller.offsetHeight)) ||
            (scroller.scrollHeight === scroller.clientHeight))
        ) {
            ev.preventDefault();
        }
    }
    scroller.addEventListener('mousewheel', callback);
    scroller.addEventListener('scroll', callback);
    scroller.addEventListener('DOMMouseScroll', callback);
};