Looking at the patch and the corresponding M-C changeset, I see that this wasn't ported: https://hg.mozilla.org/mozilla-central/rev/421820a5e759#l7.3 Something is added to a whitelist there, so maybe that avoids the security checks. Apart from that, the patch is a 1:1 port that should work in TB as well. I'll look into it.
Bug 1543815 Comment 16 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
Looking at the patch and the corresponding M-C changeset, I see that this wasn't ported: https://hg.mozilla.org/mozilla-central/rev/421820a5e759#l7.3 Something is added to a whitelist there, so maybe that avoids the security checks. Apart from that, the patch is a 1:1 port that should work in TB as well. I'll look into it. EDIT: Well, the hunk is in /browser/base/content/test/static/browser_all_files_referenced.js, so maybe not so relevant :-(