<!doctype html>
<body> <span></span> <script>
function boom() {
  var range = document.createRange();
  range.setEnd(document.body.childNodes[2], 0);
  window.addEventListener("DOMNodeInserted", f, true);
  function f() {
    window.removeEventListener("DOMNodeInserted", f, true);
    range.deleteContents();
  }
  range.deleteContents();
}
window.addEventListener("load", boom);
</script>
