layout_2020: Add an optional box size parameter to ReplacedContent::used_size_as_if_inline_element

This allow us to specify the used size when calculating size of
replaced content.

components/layout_2020/flow/inline.rs

@@ -573,6 +573,7 @@ fn layout_atomic(
             let size = replaced.contents.used_size_as_if_inline_element(
                 ifc.containing_block,
                 &replaced.style,
+                None,
                 &pbm,
             );
             let fragments = replaced