2 files changed, 28 insertions, 10 deletions
diff --git a/components/script/layout_dom/element.rs b/components/script/layout_dom/element.rs
index 9b50c9f3a2b..fd34d591f0c 100644
--- a/components/script/layout_dom/element.rs
+++ b/components/script/layout_dom/element.rs
@@ -216,11 +216,15 @@ impl<'dom> style::dom::TElement for ServoLayoutElement<'dom> {
     }
 
     fn has_part_attr(&self) -> bool {
-        false
+        self.element
+            .get_attr_for_layout(&ns!(), &local_name!("part"))
+            .is_some()
     }
 
     fn exports_any_part(&self) -> bool {
-        false
+        self.element
+            .get_attr_for_layout(&ns!(), &local_name!("exportparts"))
+            .is_some()
     }
 
     fn style_attribute(&self) -> Option<ArcBorrow<StyleLocked<PropertyDeclarationBlock>>> {
@@ -292,6 +296,17 @@ impl<'dom> style::dom::TElement for ServoLayoutElement<'dom> {
         }
     }
 
+    fn each_part<F>(&self, mut callback: F)
+    where
+        F: FnMut(&AtomIdent),
+    {
+        if let Some(parts) = self.element.get_parts_for_layout() {
+            for part in parts {
+                callback(AtomIdent::cast(part))
+            }
+        }
+    }
+
     fn has_dirty_descendants(&self) -> bool {
         unsafe {
             self.as_node()
@@ -728,8 +743,12 @@ impl<'dom> ::selectors::Element for ServoLayoutElement<'dom> {
     }
 
     #[inline]
-    fn is_part(&self, _name: &AtomIdent) -> bool {
-        false
+    fn is_part(&self, name: &AtomIdent) -> bool {
+        self.element.has_class_or_part_for_layout(
+            name,
+            &local_name!("part"),
+            CaseSensitivity::CaseSensitive,
+        )
     }
 
     fn imported_part(&self, _: &AtomIdent) -> Option<AtomIdent> {
@@ -738,7 +757,8 @@ impl<'dom> ::selectors::Element for ServoLayoutElement<'dom> {
 
     #[inline]
     fn has_class(&self, name: &AtomIdent, case_sensitivity: CaseSensitivity) -> bool {
-        self.element.has_class_for_layout(name, case_sensitivity)
+        self.element
+            .has_class_or_part_for_layout(name, &local_name!("class"), case_sensitivity)
     }
 
     fn is_html_slot_element(&self) -> bool {
diff --git a/components/script/layout_dom/node.rs b/components/script/layout_dom/node.rs
index dfb921b1ded..85b75f0b15f 100644
--- a/components/script/layout_dom/node.rs
+++ b/components/script/layout_dom/node.rs
@@ -119,9 +119,7 @@ impl<'dom> style::dom::TNode for ServoLayoutNode<'dom> {
     type ConcreteShadowRoot = ServoShadowRoot<'dom>;
 
     fn parent_node(&self) -> Option<Self> {
-        self.node
-            .composed_parent_node_ref()
-            .map(Self::from_layout_js)
+        self.node.parent_node_ref().map(Self::from_layout_js)
     }
 
     fn first_child(&self) -> Option<Self> {
@@ -302,8 +300,8 @@ impl<'dom> ThreadSafeLayoutNode<'dom> for ServoThreadSafeLayoutNode<'dom> {
     }
 
     fn parent_style(&self) -> Arc<ComputedValues> {
-        let parent = self.node.parent_node().unwrap().as_element().unwrap();
-        let parent_data = parent.borrow_data().unwrap();
+        let parent_element = self.node.traversal_parent().unwrap();
+        let parent_data = parent_element.borrow_data().unwrap();
         parent_data.styles.primary().clone()
     }