Right now we use codemirror's JavaScript mode on the website but there's a JSX mode now so we should start using that instead.

var st = [cm.state.modeGen];
    
    runMode(cm, line.text, cm.doc.mode, state, function(end, style) {
      st.push(end, style);
    }, forceToEnd);
    
    for (var o = 0; o < cm.state.overlays.length; ++o) {
      var overlay = cm.state.overlays[o], i = 1, at = 0;
      runMode(cm, line.text, overlay.mode, true, function(end, style) {
        var start = i;