fix(css): use Stylo for content visibility

moli-renderer-v8/src/native_bridge/element/styles/declaration/parse.rs

@@ -1802,12 +1802,6 @@ fn style_entries_affecting_property(entries: &[StyleEntry], property: &str) -> V
 
 fn cssom_style_property_write_uses_pdb(name: &str, value: &str) -> bool {
     let name = canonical_style_property_name(name);
-    // This Stylo build parses `content-visibility` but does not expose it
-    // through the declaration-block mutation/query surface. Keep the value in
-    // the validated side-entry path so CSSOM writes remain observable.
-    if name == "content-visibility" {
-        return false;
-    }
     if moli_css_parse::is_cssom_custom_property_name(&name) {
         return !value.is_empty() && stylo_pdb_entries_for_property(&name, value, false).is_some();
     }
@@ -2678,21 +2672,6 @@ pub(crate) fn parse_style_property_entries_with_base(
         });
     }
 
-    if name == "content-visibility" {
-        let value = css_wide_keyword(value).or_else(|| {
-            let value = value.trim().to_ascii_lowercase();
-            matches!(value.as_str(), "visible" | "auto" | "hidden").then_some(value)
-        })?;
-        return Some(ParsedStylePropertyEntries {
-            entries: vec![StyleEntry {
-                name: name.clone(),
-                value,
-                priority,
-            }],
-            affected_names: vec![name],
-        });
-    }
-
     if name == "width"
         && value
             .trim_start()
@@ -3989,6 +3968,42 @@ mod tests {
         }
     }
 
+    #[test]
+    fn content_visibility_cssom_writes_use_stylo_pdb() {
+        for (value, expected) in [
+            ("hidden", "hidden"),
+            ("AUTO", "auto"),
+            ("inherit", "inherit"),
+        ] {
+            assert!(cssom_style_property_write_uses_pdb(
+                "content-visibility",
+                value
+            ));
+            let parsed = parse_style_property_entries_for_cssom_write(
+                "content-visibility",
+                value,
+                true,
+                None,
+            )
+            .expect("content-visibility should parse through Stylo PDB");
+            assert_eq!(parsed.entries.len(), 1);
+            assert_eq!(parsed.entries[0].name, "content-visibility");
+            assert_eq!(parsed.entries[0].value, expected);
+            assert!(parsed.entries[0].priority);
+            assert!(style_entry_is_pdb_safe(&parsed.entries[0]));
+        }
+
+        assert!(
+            parse_style_property_entries_for_cssom_write(
+                "content-visibility",
+                "bogus",
+                false,
+                None,
+            )
+            .is_none()
+        );
+    }
+
     #[test]
     fn transition_pdb_parser_accepts_dynamic_numeric_longhands() {
         let shorthand = parse_style_property_entries_with_base(

moli-renderer-v8/src/native_bridge/element/styles/declaration/values.rs

@@ -1383,10 +1383,7 @@ pub(super) fn computed_style_default_value(
         "line-height" => "normal".to_owned(),
         "link-parameters" => "none".to_owned(),
         "content" => "normal".to_owned(),
-        "content-visibility" => match element_hidden_attribute_state(runtime, handle) {
-            HiddenAttributeState::UntilFound => "hidden".to_owned(),
-            HiddenAttributeState::Missing | HiddenAttributeState::Hidden => "visible".to_owned(),
-        },
+        "content-visibility" => "visible".to_owned(),
         "background-color" => "rgba(0, 0, 0, 0)".to_owned(),
         "background-attachment" => "scroll".to_owned(),
         "background-blend-mode" | "mix-blend-mode" => "normal".to_owned(),
@@ -2568,13 +2565,6 @@ fn computed_style_property_value_from_moli(
         "link-parameters" => Some(computed_non_inherited_css_keyword_property_value(
             runtime, handle, property, "none",
         )),
-        "content-visibility" => {
-            inline_style_entry_for_inline_style(runtime, handle, property).map(|_| {
-                computed_non_inherited_css_keyword_property_value(
-                    runtime, handle, property, "visible",
-                )
-            })
-        }
         "text-size-adjust" => Some(computed_text_size_adjust_value(runtime, handle)),
         "transition-property" | "transition-behavior" => {
             inline_style_entry_for_inline_style(runtime, handle, property).map(|entry| entry.value)

moli-renderer-v8/src/script_vm/tests/dom_xhr/computed_style.rs

@@ -6822,6 +6822,11 @@ fn computed_style_distinguishes_hidden_and_until_found_states() {
     target.setAttribute('hidden', value);
     values.push(read());
   }
+  target.setAttribute('hidden', 'until-found');
+  target.style.contentVisibility = 'visible';
+  values.push(`${target.style.contentVisibility}/${read()}`);
+  target.style.removeProperty('content-visibility');
+  values.push(read());
   target.removeAttribute('hidden');
   target.style.contentVisibility = 'hidden';
   values.push(`${target.style.contentVisibility}/${read()}`);
@@ -6835,7 +6840,7 @@ fn computed_style_distinguishes_hidden_and_until_found_states() {
 
     assert_eq!(
         result,
-        "block:visible|none:visible|none:visible|block:hidden|block:hidden|block:hidden|none:visible|hidden/block:hidden|hidden/block:hidden"
+        "block:visible|none:visible|none:visible|block:hidden|block:hidden|block:hidden|none:visible|visible/block:visible|block:hidden|hidden/block:hidden|hidden/block:hidden"
     );
 }