Miscellaneous build / tidy fixes.

components/layout_2020/Cargo.toml

@@ -16,7 +16,7 @@ doctest = false
 app_units = "0.7"
 atomic_refcell = "0.1.6"
 canvas_traits = { path = "../canvas_traits" }
-cssparser = "0.27"
+cssparser = "0.28"
 embedder_traits = { path = "../embedder_traits" }
 euclid = "0.20"
 fnv = "1.0"

components/layout_2020/display_list/mod.rs

@@ -474,6 +474,9 @@ impl<'a> BuilderForBoxFragment<'a> {
                 },
                 // Gecko-only value, represented as a (boxed) empty enum on non-Gecko.
                 Image::Rect(ref rect) => match **rect {},
+                Image::ImageSet(..) | Image::CrossFade(..) => {
+                    unreachable!("Shouldn't be parsed on Servo for now")
+                },
             }
         }
     }

components/layout_2020/lists.rs

@@ -7,7 +7,7 @@ use crate::dom_traversal::{NodeAndStyleInfo, NodeExt, PseudoElementContentItem};
 use crate::replaced::ReplacedContent;
 use style::properties::longhands::list_style_type::computed_value::T as ListStyleType;
 use style::properties::style_structs;
-use style::values::computed::url::UrlOrNone;
+use style::values::computed::Image;
 
 /// https://drafts.csswg.org/css-lists/#content-property
 pub(crate) fn make_marker<'dom, Node>(
@@ -21,13 +21,18 @@ where
 
     // https://drafts.csswg.org/css-lists/#marker-image
     let marker_image = || match &style.list_style_image {
-        UrlOrNone::Url(url) => Some(vec![
+        Image::Url(url) => Some(vec![
             PseudoElementContentItem::Replaced(ReplacedContent::from_image_url(
                 info.node, context, url,
             )?),
             PseudoElementContentItem::Text(" ".into()),
         ]),
-        UrlOrNone::None => None,
+        // XXX: Non-None image types unimplemented.
+        Image::ImageSet(..) |
+        Image::Rect(..) |
+        Image::Gradient(..) |
+        Image::CrossFade(..) |
+        Image::None => None,
     };
     marker_image().or_else(|| {
         Some(vec![PseudoElementContentItem::Text(