Stabilize GATs

Author: jackh726

tests/source/issue_4257.rs

@@ -1,6 +1,3 @@
-#![feature(generic_associated_types)]
-#![allow(incomplete_features)]
-
 trait Trait<T> {
     type Type<'a> where T: 'a;
     fn foo(x: &T) -> Self::Type<'_>;

tests/source/issue_4911.rs

@@ -1,4 +1,3 @@
-#![feature(generic_associated_types)]
 #![feature(min_type_alias_impl_trait)]
 
 impl SomeTrait for SomeType {

tests/source/issue_4943.rs

@@ -1,5 +1,3 @@
-#![feature(generic_associated_types)]
-
 impl SomeStruct {
     fn process<T>(v: T) -> <Self as GAT>::R<T>
     where Self: GAT<R<T> = T>

tests/target/issue_4257.rs

@@ -1,6 +1,3 @@
-#![feature(generic_associated_types)]
-#![allow(incomplete_features)]
-
 trait Trait<T> {
     type Type<'a>
     where

tests/target/issue_4911.rs

@@ -1,4 +1,3 @@
-#![feature(generic_associated_types)]
 #![feature(min_type_alias_impl_trait)]
 
 impl SomeTrait for SomeType {

tests/target/issue_4943.rs

@@ -1,5 +1,3 @@
-#![feature(generic_associated_types)]
-
 impl SomeStruct {
     fn process<T>(v: T) -> <Self as GAT>::R<T>
     where