Remove async_await gates from tests.

Author: Centril

src/test/rustdoc/async-fn.rs

@@ -1,7 +1,5 @@
 // edition:2018
 
-#![feature(async_await)]
-
 // @has async_fn/fn.foo.html '//pre[@class="rust fn"]' 'pub async fn foo() -> Option<Foo>'
 pub async fn foo() -> Option<Foo> {
     None

src/test/rustdoc/async-move-doctest.rs

@@ -1,13 +1,11 @@
 // compile-flags:--test
 // edition:2018
 
-// prior to setting the default edition for the doctest pre-parser, this doctest would fail due to
-// a fatal parsing error
+// Prior to setting the default edition for the doctest pre-parser,
+// this doctest would fail due to a fatal parsing error.
 // see https://github.com/rust-lang/rust/issues/59313
 
 //! ```
-//! #![feature(async_await)]
-//!
 //! fn foo() {
 //!     drop(async move {});
 //! }

src/test/rustdoc/edition-flag.rs

@@ -1,10 +1,7 @@
 // compile-flags:--test -Z unstable-options
 // edition:2018
 
-#![feature(async_await)]
-
 /// ```rust
-/// #![feature(async_await)]
 /// fn main() {
 ///     let _ = async { };
 /// }

src/test/ui/async-await/argument-patterns.rs

@@ -3,7 +3,6 @@
 
 #![allow(unused_variables)]
 #![deny(unused_mut)]
-#![feature(async_await)]
 
 type A = Vec<u32>;
 

src/test/ui/async-await/async-await.rs

@@ -3,8 +3,6 @@
 // edition:2018
 // aux-build:arc_wake.rs
 
-#![feature(async_await)]
-
 extern crate arc_wake;
 
 use std::pin::Pin;

src/test/ui/async-await/async-block-control-flow-static-semantics.rs

@@ -6,8 +6,6 @@
 // edition:2018
 // ignore-tidy-linelength
 
-#![feature(async_await)]
-
 fn main() {}
 
 use core::future::Future;

src/test/ui/async-await/async-closure-matches-expr.rs

@@ -1,7 +1,7 @@
 // build-pass
 // edition:2018
 
-#![feature(async_await, async_closure)]
+#![feature(async_closure)]
 
 macro_rules! match_expr {
     ($x:expr) => {}

src/test/ui/async-await/async-closure.rs

@@ -3,7 +3,7 @@
 // edition:2018
 // aux-build:arc_wake.rs
 
-#![feature(async_await, async_closure)]
+#![feature(async_closure)]
 
 extern crate arc_wake;
 

src/test/ui/async-await/async-error-span.rs

@@ -1,7 +1,6 @@
 // edition:2018
-#![feature(async_await)]
 
-// Regression test for issue #62382
+// Regression test for issue #62382.
 
 use std::future::Future;
 

src/test/ui/async-await/async-fn-elided-impl-lifetime-parameter.rs

@@ -6,8 +6,6 @@
 // check-pass
 // edition:2018
 
-#![feature(async_await)]
-
 struct Foo<'a>(&'a u8);
 
 impl Foo<'_> {