Fix validity and correctness of r63342

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).