tests/rustdoc-json: Remove more needless uses of #![no_core].

These were'nt done with regex, but don't require changes to assertions.

tests/rustdoc-json/enums/field_hidden.rs

@@ -1,11 +1,5 @@
 // Regression test for <https://github.com/rust-lang/rust/issues/100529>.
 
-#![no_core]
-#![feature(no_core, lang_items)]
-
-#[lang = "sized"]
-trait Sized {}
-
 // @has "$.index[*][?(@.name=='ParseError')]"
 // @has "$.index[*][?(@.name=='UnexpectedEndTag')]"
 // @is "$.index[*][?(@.name=='UnexpectedEndTag')].inner.variant.kind.tuple" [null]

tests/rustdoc-json/enums/kind.rs

@@ -1,11 +1,5 @@
 // ignore-tidy-linelength
 
-#![feature(no_core, lang_items)]
-#![no_core]
-
-#[lang = "sized"]
-trait Sized {}
-
 pub enum Foo {
     // @set Unit = "$.index[*][?(@.name=='Unit')].id"
     // @is "$.index[*][?(@.name=='Unit')].inner.variant.kind" '"plain"'

tests/rustdoc-json/enums/tuple_fields_hidden.rs

@@ -1,9 +1,3 @@
-#![feature(no_core, lang_items)]
-#![no_core]
-
-#[lang = "sized"]
-trait Sized {}
-
 // @set 1.1.0 = "$.index[*][?(@.docs=='1.1.0')].id"
 // @set 2.1.0 = "$.index[*][?(@.docs=='2.1.0')].id"
 // @set 2.1.1 = "$.index[*][?(@.docs=='2.1.1')].id"

tests/rustdoc-json/generic-associated-types/gats.rs

@@ -1,14 +1,5 @@
 // ignore-tidy-linelength
 
-#![no_core]
-#![feature(lang_items, no_core, arbitrary_self_types)]
-
-#[lang = "sized"]
-pub trait Sized {}
-
-#[lang = "receiver"]
-pub trait Receiver {}
-
 pub trait Display {}
 
 pub trait LendingIterator {

tests/rustdoc-json/non_lifetime_binders.rs

@@ -3,18 +3,9 @@
 #![feature(non_lifetime_binders)]
 #![allow(incomplete_features)]
 
-#![no_core]
-#![feature(lang_items, no_core)]
-
-#[lang = "sized"]
-pub trait Sized {}
-
 pub trait Trait {}
 
-#[lang = "phantom_data"]
-struct PhantomData<T_>;
-
-pub struct Wrapper<T_>(PhantomData<T_>);
+pub struct Wrapper<T_>(std::marker::PhantomData<T_>);
 
 // @count "$.index[*][?(@.name=='foo')].inner.function.generics.where_predicates[0].bound_predicate.generic_params[*]" 2
 // @is "$.index[*][?(@.name=='foo')].inner.function.generics.where_predicates[0].bound_predicate.generic_params[0].name" \"\'a\"

tests/rustdoc-json/traits/supertrait.rs

@@ -1,7 +1,5 @@
 // ignore-tidy-linelength
 
-#![feature(lang_items)]
-
 // @set loud_id = "$.index[*][?(@.name=='Loud')].id"
 pub trait Loud {}