message: Allocate var names in FrozenHeap as slice
  Summary: Use own allocation utility.
diff: @@ -398,8 +398,7 @@ impl Compiler<'_, '_, '_> {
  let used = self
  .eval
  .frozen_heap()
  - .alloc_any_display_from_debug(scope_names.used)
  - .map(|s| s.as_slice());
  + .alloc_any_slice_display_from_debug(&scope_names.used);
  let info = self.eval.module_env.frozen_heap().alloc_any(DefInfo {
  name,
  codemap: self.codemap,
  