Eclipse Community

Title is self explanatory. Ideally I'd want ESR 68 or 78 if that is possible. I know Rust is more baked in, in later releases like 91.

The SeaMonkey guys seems to be doing exactly that (backporting engine changes), albeit with Gecko instead of Goanna, and by freezing the version of Rust in order to allow for Windows 7 compatibility. They weren't able to remove all dependencies due to lack of manpower, but I suspect they may have done some work, knowing how at least some of their team tend to operate*.

I'd hop into their IRC Chat if I were you. I honestly wish they'd get more attention for what they're doing, especially around these parts - and particularly with how they were shafted by Mozilla themselves and effectively kicked off their infrastructure around the FF Quantum transition period. That shit was painful.

* One of them literally made this... thing, by the way.

It seems like the folks over at Pale Moon already removed Rust from Firefox 52 and 55 (in the form of UXP and Móbius). It should be easy to do it in FF60 or 68

60 already has Servo code, so I'd expect that to be somewhat hard.