This sets the selection to the middle of the first line, and hits the enter key.
Expected behavior: the text node is split at the cursor. The span is cloned, and everything that was split out is placed inside the clone in a new div which is a child of the root. See bug 61594.
| <span>
|   id="wrapper"
|   "First"
| <div>
|   <span>
|     "<#selection-caret> line"
|     <br>
|     "Second line"
