? I believe the Rust efforts in Firefox were largely successful. I think Servo was for experimental purposes and large parts were then added to Firefox with Quantum: https://en.wikipedia.org/wiki/Gecko_(software)#Quantum
My recollection was that those were separate changes - servo didn’t get to the stage where it could be merged, but it was absolutely the plan to build a rendering engine that outperformed every other browser before budget cuts hit.
We did port Servo’s WebRender to Firefox and shipped it everywhere. The only caveat is that it took multiple years of upgrades, fixes, and rewriting it.
