<b class="AgregarSpan"></b>
 
<script>
(function AgregarSpan() {
  var spans = document.querySelectorAll("b['AgregarSpan']");
  for(var i = 0; i < spans.length; ++i) {
    spans[i].outterHTML = "<span></span>";
  }
})()
</script>
 

<script>AgregarSpan()</script>
 
<script>
function AgregarSpan() {
  var spans = document.querySelectorAll("script");
  for(var i = 0; i < spans.length; ++i) {
    if(spans[i].innerHTML == "AgregarSpan()") {
      spans[i].outterHTML = "<span></span>";
    }
  }
}
</script>
 

if(spans[i].innerHTML.length > 14) {
  if(spans[i].innerHTML.substr(0, 12) == "AgregarSpan(" && spans[i].innerHTML.substr(0, -1) == ")" ) {
    var tmp = document.createElement("span");
    tmp.innerHTML = spans[i].innerHTML.substr(11, tmp.innerHTML.length - 12);
    spans[i].outterHTML = tmp.outterHTML;
  }
}