This was probably a regression that was introduced with the new batched
`Buffer::edit` API and was caused by providing selection ranges in a
non-ordered fashion (we were passing all the starts first and then all the
ends).
With this commit we are adding a unit test to verify the behavior of
`Editor::surround_with_bracket_pair` and changing the order in which
we pass edit ranges to respect the selection order.
7a81983c62