You're right in the sense it didn't `use::servo`, merely Servo's CSS parser `cssparser`[0] and Servo's DOM parser `html5ever`[1]. Maybe that dog can do taxes after all.
[0] https://github.com/search?q=repo%3Awilsonzlin%2Ffastrender%2...
[1] https://github.com/search?q=repo%3Awilsonzlin%2Ffastrender+h...
Taffy is related to Servo too, though apparently not officially part of the Servo project - but Servo does use it.
https://github.com/DioxusLabs/taffy
Used here (I think): https://github.com/servo/servo/tree/c639bb1a7b3aa0fd5e02b40d...