Comment 0 for bug 1045380

1. Hide a comment that you have permission to hide.

What you see:
* The background of the comment changes to dark grey. Other colors don't change.
* There is no padding between the edge of the text and the edge of the dark grey, which looks ugly.
* Since you can still see the comment, it's not obvious what the effect of choosing "Hide comment" actually was.

I suggest that choosing "Hide comment" should instead:
* set {opacity: 0.2} on the comment text (and its author and date, if they didn't make any other changes simultaneously)
* add text "Other people won’t see this comment".