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.

if (!cm.options.lineWrapping && line.text.length >= cm.options.crudeMeasuringFrom)
      return crudelyMeasureLine(cm, line);
    var display = cm.display, measure = emptyArray(line.text.length);
    var pre = buildLineContent(cm, line, measure, true).pre;
    
    
    
    
    
    
    
    
    
    
    
    if (ie && !ie_lt8 && !cm.options.lineWrapping && pre.childNodes.length > 100) {
      var fragment = document.createDocumentFragment();
      var chunk = 10, n = pre.childNodes.length;
      for (var i = 0, chunks = Math.ceil(n / chunk); i < chunks; ++i) {
        var wrap = elt("div", null, null, "display: inline-block");
        for (var j = 0; j < chunk && n; ++j) {
          wrap.appendChild(pre.firstChild);
          --n;
        }
        fragment.appendChild(wrap);
      }