clippy: fix several lint warns (#32126)

As seems #31500 still remain opened here's the next partial fix.

Fixed list: `unused_mut`, `clippy::needless_borrow`,
`clippy::match_ref_pats`, `clippy::borrow_deref_ref`, `clippy::ptr_eq`,
`clippy::unnecessary_cast`, `clippy::derivable_impls`,
`clippy::collapsible_match`, `clippy::extra_unused_lifetimes`,
`clippy::map_clone`, `clippy::manual_filter`.


- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes are part of #31500.
- [x] These changes do not require tests because are only cosmetic.

components/script/dom/servoparser/html.rs

@@ -202,7 +202,7 @@ impl Iterator for SerializationIterator {
         if let Some(SerializationCommand::OpenElement(ref e)) = res {
             self.stack
                 .push(SerializationCommand::CloseElement(e.clone()));
-            for c in rev_children_iter(&*e.upcast::<Node>()) {
+            for c in rev_children_iter(e.upcast::<Node>()) {
                 self.push_node(&c);
             }
         }