Based on the spec: https://svgwg.org/svg2-draft/single-page.html#changes-paths,

We have to

1. Removed the SVGPathSeg* and SVGAnimatedPathData interfaces and the related methods on SVGPathElement

I hope these can make the code simpler, so we could easily promote d attribute to a property.

The wpt: https://searchfox.org/mozilla-central/source/testing/web-platform/tests/svg/path/interfaces/SVGAnimatedPathData-removed.svg

Blink has removed these APIs: https://wpt.fyi/results/svg/path/interfaces/SVGAnimatedPathData-removed.svg?label=master&label=experimental&aligned&q=svg%20path, and Gecko still has non-normalized version.

We can't remove them because there's no way to get the animated values (unlike blink).