code: function ensureLineWrapped(lineView) {
      if (lineView.node == lineView.text) {
        lineView.node = elt("div", null, null, "position: relative");
        if (lineView.text.parentNode)
          lineView.text.parentNode.replaceChild(lineView.node, lineView.text);
        lineView.node.appendChild(lineView.text);
        if (ie && ie_version < 8) lineView.node.style.zIndex = 2;
      }
      return lineView.node;
    }
docs: Lines with gutter elements, widgets or a background class need to be wrapped, and have the extra elements added to the wrapper div