[csswg-drafts] [geometry] Why does DOMQuad have readonly mutable points?

tabatkins has just created a new issue for 
https://github.com/w3c/csswg-drafts:

== [geometry] Why does DOMQuad have readonly mutable points? ==
DOMQuad's p1/p2/p3/p4 attributes are readonly, which means there's no 
setter.  However, the points themselves are DOMPoint, not 
DOMPointReadonly, so they're mutable.  This seems like a bizarre 
amalgam?  You *can* mutate the quad's points, you just can't reassign 
them.

We should either make DOMQuad fully mutable (removing the readonly 
annotations), or switch them to DOMPointReadonly, rename DOMQuad to 
DOMQuadReadonly, and if necessary, add a fully mutable DOMQuad as 
well.

Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/888 using your GitHub 
account