[JuliaLowering] Kind changes in preparation for Expr-structured tree (#60706)
Three small changes, none worth doing out of context of the EST change:
- Remove `extension` and just use the three heads it represented
(`locals`, `islocal`, `isglobal`) directly. This is a reasonable idea
that we could try again sometime with more of the kinds under
`BEGIN_EXTENSION_KINDS`. For now, we aren't constrained in the `Kind`
namespace, and it's worth reducing non-simplifying differences between
trees.
- Use `inert_syntaxtree` instead of a meta-hint on `inert`. This is
mainly so it's representable in Expr, but is also visually clearer in
debugging since it's never ambiguous what tree kind we want. This
required adding it to various "ignored forms" checks, but I plan to
clean these up as we figure out the set of allowed forms in each pass.
- Tweak `hygienic_scope` to be `hygienic-scope`. Dumb, but this is one
of the very few expr-specific, macro-expansion-specific heads that
should be spelled the same, since there isn't any good opportunity to
convert it.
julia
3c712a9c - [JuliaLowering] Kind changes in preparation for Expr-structured tree (#60706)
