It's the one who edited it. But sometimes you edit an answer and the reviewer fixes something in your edit, making him the "author" of the new version of the edit. Or somebody's else, later, does it, even outside the reviewing process.
SO is a collaborative site, don't pay too much attention to the authorship of edits.
In the specific case you link to, you made the error to comment too much your edit ("I think that this edit need to be as comment, but I could not comment on this answer so I edited it."). There is a field to explain to reviewers why you edit, avoid being too verbose or personal in your edits, just focus on making the answer better if you can, without changing it too much. And don't try to make it yours, or to leave a visible mark.