<script>
if (window.layoutTestController)
     layoutTestController.dumpEditingCallbacks();
</script>
<div id="test" contenteditable="true">There&nbsp; be no line breaks in this sentence.</div>

<script>
var sel = window.getSelection();
var e = document.getElementById("test").firstChild;

sel.setPosition(e, 0);
sel.modify("move", "forward", "word");
sel.modify("move", "forward", "character");
document.execCommand("InsertHTML", false, "<div>should</div>");
</script>