Auto merge of #33600 - ollie27:rustdoc_impl_params, r=alexcrichton

rustdoc: Fix missing type parameters on impls

They were broken by #32558.

Fixes: #33592

src/test/rustdoc/issue-33592.rs

@@ -0,0 +1,23 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![crate_name = "foo"]
+
+pub trait Foo<T> {}
+
+pub struct Bar;
+
+pub struct Baz;
+
+// @has foo/trait.Foo.html '//code' 'impl Foo<i32> for Bar'
+impl Foo<i32> for Bar {}
+
+// @has foo/trait.Foo.html '//code' 'impl<T> Foo<T> for Baz'
+impl<T> Foo<T> for Baz {}