Some types have a `body: &'mir Body<'tcx>` and some have `body: &'a Body<'tcx>`. The former is more readable, so this commit converts some fo the latter to the former.
Some types have a `body: &'mir Body<'tcx>` and some have `body: &'a Body<'tcx>`. The former is more readable, so this commit converts some fo the latter to the former.