diff --git a/components/script/dom/cssrulelist.rs b/components/script/dom/cssrulelist.rs
index ac43335bbc8..3390601b1dd 100644
--- a/components/script/dom/cssrulelist.rs
+++ b/components/script/dom/cssrulelist.rs
@@ -112,8 +112,7 @@ impl CSSRuleList {
         let owner = self
             .parent_stylesheet
             .get_owner()
-            .map(DomRoot::downcast::<HTMLElement>)
-            .flatten();
+            .and_then(DomRoot::downcast::<HTMLElement>);
         let loader = owner
             .as_ref()
             .map(|element| StylesheetLoader::for_element(element));
@@ -135,7 +134,7 @@ impl CSSRuleList {
         Ok(idx)
     }
 
-    // In case of a keyframe rule, index must be valid.
+    /// In case of a keyframe rule, index must be valid.
     pub fn remove_rule(&self, index: u32) -> ErrorResult {
         let index = index as usize;
         let mut guard = self.parent_stylesheet.shared_lock().write();
@@ -163,7 +162,7 @@ impl CSSRuleList {
         }
     }
 
-    // Remove parent stylesheets from all children
+    /// Remove parent stylesheets from all children
     pub fn deparent_all(&self) {
         for rule in self.dom_rules.borrow().iter() {
             if let Some(r) = rule.get() {