1 files changed, 15 insertions, 0 deletions
diff --git a/servo/components/style/selector_map.rs b/servo/components/style/selector_map.rs
index 2b8d6add55..439fd414a6 100644
--- a/servo/components/style/selector_map.rs
+++ b/servo/components/style/selector_map.rs
@@ -330,6 +330,10 @@ impl SelectorMap<Rule> {
     ) where
         E: TElement,
     {
+        use selectors::matching::IncludeStartingStyle;
+
+        let include_starting_style =
+            matches!(matching_context.include_starting_style, IncludeStartingStyle::Yes);
         for rule in rules {
             if !matches_selector(
                 &rule.selector,
@@ -352,6 +356,17 @@ impl SelectorMap<Rule> {
                 }
             }
 
+            if rule.is_starting_style {
+                // Set this flag if there are any rules inside @starting-style. This flag is for
+                // optimization to avoid any redundant resolution of starting style if the author
+                // doesn't specify for this element.
+                matching_context.has_starting_style = true;
+
+                if !include_starting_style {
+                    continue;
+                }
+            }
+
             matching_rules.push(rule.to_applicable_declaration_block(cascade_level, cascade_data));
         }
     }