Handle <select multiple> about dom99 HOT 3 OPEN

To read current value, where select is the html node

Array.from(select.selectedOptions).map(option => {
    return option.value;
);

from dom99.

To write, cannot use selectedOptions directly. Instead go through select.options and set or remove "selected" attribute

from dom99.

One problem is that now arrays are used already for data-list

from dom99.