As a consequence of https://github.com/atom/atom/pull/15378, we are now
able to render highlight decorations in a separate div, as opposed to
having an highlight container for each tile.
Code-wise this is much simpler, because highlights spanning multiple
tiles can be represented via a single region and don't need to be split
across the tiles they span anymore. As a byproduct, performance should
improve as well, because the number of nodes that need to be managed
should decrease significantly.
This also fixes https://github.com/atom/atom/issues/15449, and other
similar rendering artifacts, because highlight decoration DOM nodes
won't need to move between tiles anymore when their position changes.
At the cost of a very minimal reduction in layout performance, we gain
reliable rendering at all line heights and don't have to worry about
characters that extend above/below the footprint of a line.
Signed-off-by: Nathan Sobo <nathan@github.com>
...because packages like `.git-diff` are relying on this behavior to
position their decorations. This didn't seem to degrade layout times, so
it makes sense to just add it to keep package breakage to a minimum.
