- Ensure that both sides are passed the appropriate companion data to
preserve spacers when syncing
- Remove companion handling in codepaths related to range folding, since
this isn't supported in the side-by-side diff
- Move handling of buffer folding into the block map
- Rework `set_companion` to handle both `DisplayMap`s at once
- DRY some code around block map syncing in the `DisplayMap`
TODO:
- [x] diagnose and fix issue that causes balancing blocks not to render
properly when they are adjacent to spacers (e.g. merge conflict buttons)
- [x] clear balancing blocks when clearing companion
- [x] additional tests: interaction between spacers and balancing
blocks, resizing
Release Notes:
- N/A
Cole Miller
11acd9602d