CVE-2026-83617: xmldom: requireWellFormed element/attribute name validation is bypassable via an embedded line terminator

An embedded line terminator bypasses the requireWellFormed serializer check for element and attribute names. The check was added to fix GHSA-w2rr-34g9-rvrj and GHSA-4w3w-2rp5-g8jm; a name whose first line is well-formed slips past it and is serialized verbatim, so the characters after the line terminator break out of the start/end tag or attribute. Callers who enabled requireWellFormed specifically to neutralize those name-injection issues remain exposed.