Firefox Content Editable remove "help elements"

Question

I have a huge issue with Firefox, as soon as I create a content editable table, it keeps importing a bunch of "help elements" that I do not want.

Reproduce: Open fiddle with firefox (personally, Im using 48.0).

See fiddle: https://jsfiddle.net/fronjv5o/

<div id="content" contenteditable="true">
<table>
<tr>
  <td>
    hello world
  </td>
</tr>
</table>
</div> 

My question is, how do I remove those "help elements" from ever showing their ugly face again?

In case it wasnt clear enough here is what I am refering too:

Answer 1

And after pouring an hour into this only to find the solution here: Contenteditable table row,column modifier

But basically:

 document.execCommand("enableInlineTableEditing", null, false);

once the DOM has been loaded.