How to add rows to TableElement in Dart?

I'm playing with Dart, and I'm trying to create a new TableElement with a header and one row in the tbody.

  TableElement table = new TableElement();

  Element head = table.createTHead();
  TableRowElement headerRow =  table.tHead.insertRow(-1);
  headerRow.insertCell(0).text = "9";
  headerRow.insertCell(1).text = "aaa";
  headerRow.insertCell(2).text = "bbb";
  headerRow.insertCell(3).text = "ccc";

  var tBody = table.createTBody();
  TableRowElement newLine = table.insertRow(-1); // add at the end
  newLine.insertCell(0).text = "9";
  newLine.insertCell(1).text = "aaa";
  newLine.insertCell(2).text = "bbb";
  newLine.insertCell(3).text = "ccc";

Unfortunately, both rows end up in the thead section. On top of that, if I leave only

  TableElement table = new TableElement();

  var tBody = table.createTBody();
  TableRowElement newLine = table.insertRow(-1); // add at the end
  newLine.insertCell(0).text = "9";
  newLine.insertCell(1).text = "aaa";
  newLine.insertCell(2).text = "bbb";
  newLine.insertCell(3).text = "ccc";

the row gets to tbody section, as expected. Any Ideas? Dart SDK 9474.