Fix the review request actions bar when empty.
Review Request #7375 — Created June 4, 2015 and submitted
When there was nothing to display in the review request actions bar, it'd appear as a thin line, which looked horrible. This was because there wasn't any content on the bar to force the height to anything reasonable. We already have a :before style, with no padding or content. This change updates it to have some content (which is hidden but still takes up room), and the same padding that the actions themselves have. Also, I previously swapped the names of two variables (the ones use for vert and horiz padding on actions). The vert was containing the horiz padding, and vice-versa. These have been fixed up.
Viewed an interdiff, which has no actions. Saw that the bar was the correct height.