Fix jumpy scroll

[gdbroman]

• react-virtualized was not built for scrolling from the bottom. When scrolling from the bottom, the whole list shifts because the scroll position doesn't account for the newly loaded row heights. The maintainer said it himself, but won't fix it. Dynamic height + scrolling up (when the upper cells aren't loaded yet) bvaughn/react-virtualized#610
• As an alternative you can achieve scroll from bottom using transform: scaleY(-1) on the container + individual rows, as well as reversing the data order. Then the loading algorithm can run top to bottom, without shift, while the experience is scrolling from the bottom.