Merge EditorScrollViewComponent into Editor

I don't think that this component was really carrying its weight. Its
render function basically passed through directly to other components
that updated between renders, but didn't contain any content on its
own that actually changed after the first render.

React components seem to carry overhead, so I want every component we
use to count. Also, I'm considering circumventing some of React's
standard update logic for performance reasons, and making the structure
more shallow will help with that.
:lipstick: EditorComponent method order
Merge pull request #2477 from atom/ns-react-remove-scroll-view-component

Merge EditorScrollViewComponent into EditorComponent