Check the child is unstyled without creating element data in preproce…

…ss_children.

If we check it and skip the child after ensure_element_data() call,
the child will have an empty element data, so we will succeed
element_data.is_some() check unexpectedly.

components/style/traversal.rs

@@ -862,14 +862,14 @@ where
             None => continue,
         };
 
-        let mut child_data =
-            unsafe { D::ensure_element_data(&child).borrow_mut() };
-
         // If the child is unstyled, we don't need to set up any restyling.
-        if !child_data.has_styles() {
+        if child.borrow_data().map_or(true, |d| !d.has_styles()) {
             continue;
         }
 
+        let mut child_data =
+            unsafe { D::ensure_element_data(&child).borrow_mut() };
+
         trace!(" > {:?} -> {:?} + {:?}, pseudo: {:?}",
                child,
                child_data.restyle.hint,