Revert "pre-expansion gate crate_visibility_modifier"

This reverts commit 04c661b.

Author: eddyb

src/libsyntax/feature_gate/check.rs

@@ -661,6 +661,14 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
         }
         visit::walk_impl_item(self, ii)
     }
+
+    fn visit_vis(&mut self, vis: &'a ast::Visibility) {
+        if let ast::VisibilityKind::Crate(ast::CrateSugar::JustCrate) = vis.node {
+            gate_feature_post!(&self, crate_visibility_modifier, vis.span,
+                               "`crate` visibility modifier is experimental");
+        }
+        visit::walk_vis(self, vis)
+    }
 }
 
 pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute],

src/test/ui/feature-gates/feature-gate-crate_visibility_modifier.rs

@@ -5,7 +5,4 @@ crate struct Bender { //~ ERROR `crate` visibility modifier is experimental
     water: bool,
 }
 
-macro_rules! accept_vis { ($v:vis) => {} }
-accept_vis!(crate);  //~ ERROR `crate` visibility modifier is experimental
-
 fn main() {}

src/test/ui/feature-gates/feature-gate-crate_visibility_modifier.stderr

@@ -7,15 +7,6 @@ LL | crate struct Bender {
    = note: for more information, see https://github.com/rust-lang/rust/issues/53120
    = help: add `#![feature(crate_visibility_modifier)]` to the crate attributes to enable
 
-error[E0658]: `crate` visibility modifier is experimental
-  --> $DIR/feature-gate-crate_visibility_modifier.rs:9:13
-   |
-LL | accept_vis!(crate);
-   |             ^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/53120
-   = help: add `#![feature(crate_visibility_modifier)]` to the crate attributes to enable
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0658`.