rustdoc: remove redundant item kind class from `.item-decl > pre`

This class originated in the very first commit of `rustdoc_ng`, and was used
to add a color border around the item decl based on its kind.

https://github.com/rust-lang/rust/blob/4fd061c426902b0904c65e64a3780b21f9ab3afb/src/rustdoc_ng/html/static/main.css#L102-L106

The item decl no longer has a border, and there aren't any
kind-specific styles in modern rustdoc's rendering of this UI item.

Most of this commit is updating test cases so that they use `item-decl` to
find the `<pre>` tag instead of relying on the fact that the class name
had `rust {kind}` in it while other `<pre>` tags only had class `rust`.

1 files changed, 3 insertions, 3 deletions

diff --git a/tests/rustdoc/attributes.rs b/tests/rustdoc/attributes.rs
index a36dadced87..70e2e5c2950 100644
--- a/tests/rustdoc/attributes.rs
+++ b/tests/rustdoc/attributes.rs
@@ -1,13 +1,13 @@
 #![crate_name = "foo"]
 
-// @has foo/fn.f.html '//*[@class="rust fn"]' '#[no_mangle]'
+// @has foo/fn.f.html '//div[@class="item-decl"]/pre[@class="rust"]' '#[no_mangle]'
 #[no_mangle]
 pub extern "C" fn f() {}
 
-// @has foo/fn.g.html '//*[@class="rust fn"]' '#[export_name = "bar"]'
+// @has foo/fn.g.html '//div[@class="item-decl"]/pre[@class="rust"]' '#[export_name = "bar"]'
 #[export_name = "bar"]
 pub extern "C" fn g() {}
 
-// @has foo/struct.Repr.html '//*[@class="item-decl"]' '#[repr(C, align(8))]'
+// @has foo/struct.Repr.html '//div[@class="item-decl"]' '#[repr(C, align(8))]'
 #[repr(C, align(8))]
 pub struct Repr;