Edit: In Blink, the layer/compositing system extends to SVG elements inside SVG tags, as well, and in WebKit, it doesn’t yet, but there is an active years-long effort going back to 2019 that will eventually land: https://youtu.be/WxqJFxiprrU?si=dhQIgW1V4yS_Ca4s Compositing and using the GPU seems like a complex but important part of rendering in a browser, and a case where it could be good to implement the kind of system that other browsers have arrived at after years of iteration, when it comes time to do so.
Will the JS engine still be LibJS?