Anonymous boxes that wrap inlines should not inherit overflow (#30579)

In legacy layout, anonymous text wrappers were inheriting the `overflow`
and `text-overflow` properties. This results in the creation of extra
clipping for these anonymous wrappers which could clip away floats. We
will likely implement `text-overflow` differently in non-legacy layout.

This change marks all legacy layout pseudo elements as "legacy" and also
adds a new pseudo element for non-legacy layout that does not inherit
`overflow`.

Fixes #30562.

Co-authored-by: Oriol Brufau <obrufau@igalia.com>

components/layout_2020/dom_traversal.rs

@@ -228,7 +228,7 @@ fn traverse_pseudo_element_contents<'dom, Node>(
                         .stylist
                         .style_for_anonymous::<Node::ConcreteElement>(
                             &context.shared_context().guards,
-                            &PseudoElement::ServoText,
+                            &PseudoElement::ServoAnonymousBox,
                             &info.style,
                         )
                 });