Fix GH-11625: DOMElement::replaceWith() doesn't replace node with DOMDocumentFragment but just deletes node or causes wrapping <></> depending on libxml2 version

Depending on the libxml2 ver

Fix GH-11625: DOMElement::replaceWith() doesn't replace node with DOMDocumentFragment but just deletes node or causes wrapping <></> depending on libxml2 version

Depending on the libxml2 version, the behaviour is either to not
render the fragment correctly, or to wrap it inside <></>. Fix it by
unpacking fragments manually. This has the side effect that we need to
move the unlinking check in the replacement function to earlier because
the empty child list is now possible in non-error cases.
Also fixes a mistake in the linked list management.

Closes GH-11627.

show more ...