Auto merge of #20482 - brainlessdeveloper:list-style-image-computed, r=emilio

Implement a URL-generic type for ListStyleImage

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This should fix the following two "expected to fail" tests described in https://github.com/servo/servo/issues/18015:

- getComputedStyle(elem) for url() listStyleImage uses the resolved URL
  and elem.style uses the original URL

- getComputedStyle(elem) for url() listStyle uses the resolved URL
  and elem.style uses the original URL

I updated the test failure expectations by removing the corresponding `.ini` file.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #18015 (github issue number if applicable).

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- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/layout/construct.rs

@@ -52,11 +52,10 @@ use style::context::SharedStyleContext;
 use style::dom::TElement;
 use style::logical_geometry::Direction;
 use style::properties::ComputedValues;
-use style::properties::longhands::list_style_image;
 use style::selector_parser::{PseudoElement, RestyleDamage};
 use style::servo::restyle_damage::ServoRestyleDamage;
-use style::values::Either;
 use style::values::computed::counters::ContentItem;
+use style::values::generics::url::UrlOrNone as ImageUrlOrNone;
 use table::TableFlow;
 use table_caption::TableCaptionFlow;
 use table_cell::TableCellFlow;
@@ -1278,13 +1277,13 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
                                 -> ConstructionResult {
         let flotation = FloatKind::from_property(flotation);
         let marker_fragments = match node.style(self.style_context()).get_list().list_style_image {
-            list_style_image::computed_value::T(Either::First(ref url_value)) => {
+            ImageUrlOrNone::Url(ref url_value) => {
                 let image_info = Box::new(ImageFragmentInfo::new(
                     url_value.url().map(|u| u.clone()), node, &self.layout_context
                 ));
                 vec![Fragment::new(node, SpecificFragmentInfo::Image(image_info), self.layout_context)]
             }
-            list_style_image::computed_value::T(Either::Second(_none)) => {
+            ImageUrlOrNone::None => {
                 match ListStyleTypeContent::from_list_style_type(node.style(self.style_context())
                                                                      .get_list()
                                                                      .list_style_type) {