We recently removed the "up here" arrows on item-infos, and adjusted
vertical spacing so that even without the arrow, it would be visually
clear which item the item-info belonged to. The new CSS styles for
vertical spacing only applied to toggles, though. This missed
non-toggled impl blocks - for instance, those without any methods, like
https://doc.rust-lang.org/nightly/std/marker/trait.Send.html#implementors.
The result was lists of implementors that were spaced too closely. This
PR fixes the spacing by making it apply to non-toggled impl blocks as
well.
This also fixes an issue where item-infos were displayed too far below
their items. That was a result of display: table on .item-info .stab.
Changed that to display: inline-block.
