FWIW,
If change the following line of attachment 9249866 [details]
`document.body.appendChild(newLink);`
to
`newLink = document.body.appendChild(newLink);`
then it works.
Bug 1739929 Comment 13 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
~~FWIW,
If change the following line of attachment 9249866 [details]
`document.body.appendChild(newLink);`
to
`newLink = document.body.appendChild(newLink);`
then it works.~~
Sorry, this is wrong.