No line numbers but you can log(...msg...) to this console and see it on a mobile device

Mobile JS Console

//mobile console
(function() {
    var el = document.createElement('div'),
    s = el.style;
    //s.display = 'none'; //enable for production
    s.position = 'fixed';
    s.bottom = '0px';
    s.left = '0px';
    s.background = 'white';
    s.width = '100%';
    s.height = '97px';
    s.borderTop = '1px solid black';
    s.fontSize = '10px';
    s.fontFamily = 'Verdana';
    s.padding = '4px';
    s.lineHeight = '10px';
    s.zIndex = 999999;
    s.overflow = 'hidden';
    s.overflowY = 'scroll';
    document.body.appendChild(el);
    //log
    window.log = function(msg) {
        el.innerHTML += msg + '<br />';
        el.scrollTop = 9999999;
        console.log(msg);
    };
}());