Yeah, I got one more. 
In Firefox about:config…
…do you see a “pref” there… called gl.ignore-dx-interop2-blacklist ?
I have no idea what that does (I need to web-search it)… but you could try setting that to true (by double-clicking on the ‘false’ beside that entry).
It’s just a guess… one more thing to try.
Also, nice job on the investigation info you provided in your last post. Well done. We’ll be thinking about this… carefully. It is important to us.
Could you please give us your EXACT firefox version number… including the ‘esr’ part, if you are on the Extended Support Release “branch”. I am. I currently run 60.8.0esr (32-bit). I think the ‘esr’ means that you/I/we are not on the Firefox ‘Quantum’ branch. I took the esr branch… because Quantum branch killed my ad-blockers, but esr doesn’t. That was a long time ago (at first Quantum release time), and the ad-blockers are now probably updated to work on Quantum branch, too.
Sidenote: FF Quantum needs its extensions/plugins coded in a different way than before, so many of the well-established extensions/plugins… didn’t work when Quantum was released. One plugin I use ALWAYS… is the “hide tab bar when only one tab open”… because, in my opinion, Firefox is/was trying to “ram” tabbed-browsing down our throats. To be frank, I hate tabs. With tabbed-browsing, ALT-tab (and Windowsbutton-tab) no longer works to switch FF windows… because all the browser windows are in the same app… a single tabbed-browsing FF. SO, it was what? Control-tab to switch tab-windows, after that? NO THANKS. (left thumb needs to reach too far beneath left palm, to reach control key). My fingers are already well addicted to the alt-tab movement.
I win. Firefox’s railroading toward tabbed-browsing… loses. heh
Back on this AA issue, I’m not sure about anything. I would love to see a BJS playground demo where the anti-aliases are failing, and to see those two errors you listed… happen on MY Firefox… easier for me/others to do tests. I am currently reading about “Live reload enabled.” line/feature… learning what it is and looking for clues, there. Also reading about FXAA and MSAA… trying to get educated. When browsing firefox’s about:config URL/page, search for MSAA, as well. IT returns a couple of interestingly-named options/prefs, too. hmm.
Let’s welcome comments from EVERYONE… see who knows what. Stay tuned, and keep reporting discoveries… thx!