When deleting the last ordered list item in a table cell, that it is the root editable element, we must delete the whole ordered list:

Before:
| <table>
|   border="1"
|   <tbody>
|     <tr>
|       <td>
|         contenteditable="true"
|         <ol>
|           <li>
|             id="li"
|             <#selection-caret>
|             <br>

After:
| <table>
|   border="1"
|   <tbody>
|     <tr>
|       <td>
|         contenteditable="true"
|         <div>
|           <#selection-caret>
|           <br>