Elide lifetimes where possible after rustup (#34824)

The new version of rust allows us to elide some lifetimes and clippy is
now complaining about this. This change elides them where possible and
removes the clippy exceptions.

Fixes #34804.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/layout_2020/traversal.rs

@@ -30,7 +30,7 @@ impl<'a> RecalcStyle<'a> {
 }
 
 #[allow(unsafe_code)]
-impl<'a, 'dom, E> DomTraversal<E> for RecalcStyle<'a>
+impl<'dom, E> DomTraversal<E> for RecalcStyle<'_>
 where
     E: TElement,
     E::ConcreteNode: 'dom + LayoutNode<'dom>,