serialization of shadowrootcustomelementregistry should compare to document's registry not the host's #11892
Description
What is the issue with the HTML Standard?
As per this DOM issue .attachShadow was changed to use the global registry by default rather than the host's. However this change isn't reflected in the serialization steps of shadow roots in the HTML spec:
If current node's custom element registry is not shadow's custom element registry, then append " shadowrootcustomelementregistry=""".
I believe the change here should be to simply to check the current node's document' registry instead.