Make Layout 2013 style a superset of Layout 2020 style

This is the first step toward removing the compile-time difference in
style between Layout 2020 and Layout 2013.

2 files changed, 14 insertions, 5 deletions

diff --git a/components/layout/construct.rs b/components/layout/construct.rs
index c3ebed7d1a3..d9531be391f 100644
--- a/components/layout/construct.rs
+++ b/components/layout/construct.rs
@@ -73,6 +73,7 @@ use style::selector_parser::{PseudoElement, RestyleDamage};
 use style::servo::restyle_damage::ServoRestyleDamage;
 use style::values::computed::Image;
 use style::values::generics::counters::ContentItem;
+use style::LocalName;
 
 /// The results of flow construction for a DOM node.
 #[derive(Clone)]
@@ -865,6 +866,15 @@ where
                                 Box::new(UnscannedTextFragmentInfo::new(string.into(), None));
                             SpecificFragmentInfo::UnscannedText(info)
                         },
+                        ContentItem::Attr(attr) => {
+                            let element = node.as_element().expect("Expected an element");
+                            let attr_val = element
+                                .get_attr(&attr.namespace_url, &LocalName::from(&*attr.attribute));
+                            let string = attr_val.map_or("".to_string(), |s| s.to_string());
+                            let info =
+                                Box::new(UnscannedTextFragmentInfo::new(string.into(), None));
+                            SpecificFragmentInfo::UnscannedText(info)
+                        },
                         content_item => {
                             let content_item =
                                 Box::new(GeneratedContentInfo::ContentItem(content_item));
diff --git a/components/layout/generated_content.rs b/components/layout/generated_content.rs
index 89f65732761..90e17fe3e8c 100644
--- a/components/layout/generated_content.rs
+++ b/components/layout/generated_content.rs
@@ -198,10 +198,6 @@ impl<'a, 'b> ResolveGeneratedContentFragmentMutator<'a, 'b> {
                         RenderingMode::Suffix(".\u{00a0}"),
                     )
                 },
-                GeneratedContentInfo::Empty |
-                GeneratedContentInfo::ContentItem(ContentItem::String(_)) => {
-                    // Nothing to do here.
-                },
                 GeneratedContentInfo::ContentItem(ContentItem::Counter(
                     ref counter_name,
                     counter_style,
@@ -272,8 +268,11 @@ impl<'a, 'b> ResolveGeneratedContentFragmentMutator<'a, 'b> {
                         self.traversal.quote -= 1
                     }
                 },
+                GeneratedContentInfo::Empty |
+                GeneratedContentInfo::ContentItem(ContentItem::String(_)) |
+                GeneratedContentInfo::ContentItem(ContentItem::Attr(_)) |
                 GeneratedContentInfo::ContentItem(ContentItem::Image(..)) => {
-                    unreachable!("Servo doesn't parse content: url(..) nor image-set(..) yet")
+                    // Nothing to do here.
                 },
             }
         };