Fix validity and correctness of
r63342
The name attribute may only be used on <a> if an id attribute with
identical value is given on the same element. I moved the id to the tr
so it leaves a bit of space at the top, rather than using a name
attribute at all. Also, we need to call Sanitizer::escapeId() on the
group key, lest people use spaces or something in the group key (not
advisable, but possible).