resolve: Remove visibility hacks for enum variants and trait items

Special treatment like this was necessary before `pub(restricted)` had been implemented and only two visibilities existed - `pub` and non-`pub`.
Now it's no longer necessary and the desired behavior follows from `pub(restricted)`-style visibilities naturally assigned to enum variants and trait items.

compiler/rustc_resolve/src/lib.rs

@@ -750,27 +750,12 @@ impl<'a> NameBinding<'a> {
     fn is_possibly_imported_variant(&self) -> bool {
         match self.kind {
             NameBindingKind::Import { binding, .. } => binding.is_possibly_imported_variant(),
-            _ => self.is_variant(),
-        }
-    }
-
-    // We sometimes need to treat variants as `pub` for backwards compatibility.
-    fn pseudo_vis(&self) -> ty::Visibility {
-        if self.is_variant() && self.res().def_id().is_local() {
-            ty::Visibility::Public
-        } else {
-            self.vis
-        }
-    }
-
-    fn is_variant(&self) -> bool {
-        matches!(
-            self.kind,
             NameBindingKind::Res(
                 Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), _),
                 _,
-            )
-        )
+            ) => true,
+            NameBindingKind::Res(..) | NameBindingKind::Module(..) => false,
+        }
     }
 
     fn is_extern_crate(&self) -> bool {