Review Firefox 139 Developer + Release Notes

We should read over the notes put out by Mozilla and open any further audit issues if necessary.

Developer Notes

• https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/139

Release Note:

• 139.0: https://www.mozilla.org/en-US/firefox/139.0/releasenotes/
• 139.0.1: https://www.mozilla.org/en-US/firefox/139.0.1/releasenotes/