diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index ace76867217..f4081ed7aa5 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -814,6 +814,21 @@ impl<'le> GeckoElement<'le> {
         (!self.as_node().is_in_shadow_tree() && self.has_xbl_binding_parent())
     }
 
+    /// Returns true if this node is the shadow root of an use-element shadow tree.
+    #[inline]
+    fn is_root_of_use_element_shadow_tree(&self) -> bool {
+        if !self.is_root_of_anonymous_subtree() {
+            return false
+        }
+        match self.parent_element() {
+            Some(e) => {
+                e.local_name() == &*local_name!("use") &&
+                    e.namespace() == &*ns!("http://www.w3.org/2000/svg")
+            },
+            None => false,
+        }
+    }
+
     fn css_transitions_info(&self) -> FnvHashMap<LonghandId, Arc<AnimationValue>> {
         use gecko_bindings::bindings::Gecko_ElementTransitions_EndValueAt;
         use gecko_bindings::bindings::Gecko_ElementTransitions_Length;
@@ -2103,10 +2118,14 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
                 }
                 true
             }
+            NonTSPseudoClass::MozNativeAnonymous => {
+                self.is_in_native_anonymous_subtree()
+            }
+            NonTSPseudoClass::MozUseShadowTreeRoot => {
+                self.is_root_of_use_element_shadow_tree()
+            }
             NonTSPseudoClass::MozTableBorderNonzero |
-            NonTSPseudoClass::MozBrowserFrame |
-            NonTSPseudoClass::MozNativeAnonymous |
-            NonTSPseudoClass::MozUseShadowTreeRoot => unsafe {
+            NonTSPseudoClass::MozBrowserFrame => unsafe {
                 Gecko_MatchesElement(pseudo_class.to_gecko_pseudoclasstype().unwrap(), self.0)
             },
             NonTSPseudoClass::MozIsHTML => {
@@ -2235,20 +2254,10 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
 
     #[inline]
     fn blocks_ancestor_combinators(&self) -> bool {
-        if !self.is_root_of_anonymous_subtree() {
-            return false
-        }
-
-        match self.parent_element() {
-            Some(e) => {
-                // If this element is the shadow root of an use-element shadow
-                // tree, according to the spec, we should not match rules
-                // cross the shadow DOM boundary.
-                e.local_name() == &*local_name!("use") &&
-                e.namespace() == &*ns!("http://www.w3.org/2000/svg")
-            },
-            None => false,
-        }
+        // If this element is the shadow root of an use-element shadow tree,
+        // according to the spec, we should not match rules cross the shadow
+        // DOM boundary.
+        self.is_root_of_use_element_shadow_tree()
     }
 }