function $b013befce1f6217f$var$onDocumentTouchStart() {
    if ($b013befce1f6217f$var$currentInput.isTouch) return;
    $b013befce1f6217f$var$currentInput.isTouch = true;
    if (window.performance) document.addEventListener('mousemove', $b013befce1f6217f$var$onDocumentMouseMove);
}
When a `touchstart` event is fired, it's assumed the user is using touch
input. We'll bind a `mousemove` event listener to listen for mouse input in
the future. This way, the `isTouch` property is fully dynamic and will handle
hybrid devices that use a mix of touch + mouse input.