As discussed and suggested by Julien Chaffraix on https://bugs.webkit.org/show_bug.cgi?id=80773, we need to create a separate bug for the rendering problem of MathML msub anonymous child render. Currently, msub anonymous child render is rendered as anonymous table by default which shouldn't be correct. I think the expected style should be close to mtable render.
Created attachment 177877 [details] Proposed change.
Comment on attachment 177877 [details] Proposed change. Forget this patch, it's posted on the wrong bug.
Unblock this bug.
I'm not sure what this bug is about, but AFAIK msub now uses flexboxes.