Fix hydration error when transition contains comment children

Editor assessment

A well-formed bug-fix commit: the ssr scope is correct for hydration behavior, the subject describes the trigger — a transition containing comment children — precisely enough to search for later, and the blank line before the 'fix #5351' footer follows the spec's header/body separation. The double use of 'fix', once as the type and once opening the subject, is redundant; dropping it would lose nothing. The subject sits just under the 72-character limit, so truncation is not a concern. For changelog automation this lands cleanly under bug fixes for a patch release, and the issue reference gives maintainers the reproduction context the missing body would otherwise need to carry.