MathML CG decision: https://github.com/mathml-refresh/mathml/issues/30#issuecomment-487748458
It does not seem the align attribute is implemented for munderover/munder/mover.
Pull request: https://github.com/WebKit/WebKit/pull/3841
Committed 254098@main (4515a6cc6d0b): <https://commits.webkit.org/254098@main> Reviewed commits have been landed. Closing PR #3841 and removing active labels.
<rdar://problem/99488951>