Do not set dirty out-of-doc nodes

components/style/dom.rs

@@ -185,6 +185,9 @@ pub trait TNode: Sized + Copy + Clone + Debug + NodeInfo + PartialEq {
         DomChildren(self.first_child())
     }
 
+    /// Returns whether the node is attached to a document.
+    fn is_in_document(&self) -> bool;
+
     /// Returns whether the node is connected.
     fn is_connected(&self) -> bool;
 

components/style/gecko/wrapper.rs

@@ -421,6 +421,11 @@ impl<'ln> TNode for GeckoNode<'ln> {
         self.get_bool_flag(nsINode_BooleanFlag::IsInDocument)
     }
 
+    #[inline]
+    fn is_connected(&self) -> bool {
+        self.get_bool_flag(nsINode_BooleanFlag::IsConnected)
+    }
+
     fn traversal_parent(&self) -> Option<GeckoElement<'ln>> {
         self.flattened_tree_parent().and_then(|n| n.as_element())
     }