LayoutTests/fast/dom/delete-contents.html

<!-- This test was derived from a real case inside the Mail application, bug 4598149-->

<div id="mydiv">01234</div>

<script>

var txt = document.getElementById("mydiv").firstChild;
window.getSelection().setBaseAndExtent(txt, 0, txt, 5)
var r = window.getSelection().getRangeAt(0);
r.deleteContents();
r.insertNode(document.createElement("div"));

</script>