[css-ui] Should the outer edge of an outline following border-radius use the box-shadow spread algorithm?

[wangxianzhu]

css-backgrounds defines a box-shadow with border-radius spread algorithm (https://www.w3.org/TR/css-backgrounds-3/#shadow-shape) to achieve continuity or the radii of the outer edge when border-radius changes between zero to non-zero. The algorithm will be revised for #7103. The reason for applying the algorithm to box-shadow seems also apply to outlines, so should css-ui consider adopting the algorithm?