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 (n == null) return null;
      }
      return {line: n, handle: line, text: line.text, gutterMarkers: line.gutterMarkers,
              textClass: line.textClass, bgClass: line.bgClass, wrapClass: line.wrapClass,
              widgets: line.widgets};
    },
    getViewport: function() { return {from: this.display.showingFrom, to: this.display.showingTo};},
    addWidget: function(pos, node, scroll, vert, horiz) {
      var display = this.display;
      pos = cursorCoords(this, clipPos(this.doc, pos));
      var top = pos.bottom, left = pos.left;
      node.style.position = "absolute";
      display.sizer.appendChild(node);
      if (vert == "over") {
        top = pos.top;
      } else if (vert == "above" || vert == "near") {
        var vspace = Math.max(display.wrapper.clientHeight, this.doc.height),
        hspace = Math.max(display.sizer.clientWidth, display.lineSpace.clientWidth);
        
        if ((vert == 'above' || pos.bottom + node.offsetHeight > vspace) && pos.top > node.offsetHeight)
          top = pos.top - node.offsetHeight;
        else if (pos.bottom + node.offsetHeight <= vspace)
          top = pos.bottom;
        if (left + node.offsetWidth > hspace)
          left = hspace - node.offsetWidth;
      }
      node.style.top = top + "px";
      node.style.left = node.style.right = "";
      if (horiz == "right") {
        left = display.sizer.clientWidth - node.offsetWidth;