get_tab_index(): use a for loop with early-exit for performance

}

function get_tab_index(tabId) {

    var res = 0;

    gradioApp().getElementById(tabId).querySelector('div').querySelectorAll('button').forEach(function(button, i) {

        if (button.className.indexOf('selected') != -1) {

            res = i;

    let buttons = gradioApp().getElementById(tabId).querySelector('div').querySelectorAll('button');

    for (let i = 0; i < buttons.length; i++) {

        if (buttons[i].classList.contains('selected')) {

            return i;

        }

    });

    return res;

    }

    return 0;

}

function create_tab_index_args(tabId, args) {