Update hidden extern crate test

Author: chojs23

tests/rustdoc-html/display-hidden-items.rs

@@ -5,9 +5,8 @@
 #![crate_name = "foo"]
 
 //@ has 'foo/index.html'
-//@ has - '//dt/span[@title="Hidden item"]' '👻'
 
-//@ has - '//dt/span[@title="Hidden item"]' '👻'
+//@ matches - '//dt[code]' 'pub extern crate .*hidden_core;.*👻'
 //@ has - '//dt/code' 'pub extern crate core as hidden_core;'
 #[doc(hidden)]
 pub extern crate core as hidden_core;