Function mount

docs/app/js/sanddance-app.js:6698–6701

(element, container)

    return !!el.nodeType;
}
function mount(element, container) {
    container.innerHTML = "";
    if (element) addChild(container, element);
}
function findElementByChildPositions(childPositions, container) {
    let element = container || document.body;
    let childPosition;