auto merge of #5459 : jdm/servo/reflowquery, r=saneyuki

components/script/dom/window.rs

@@ -537,7 +537,7 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
         debug!("script: performing reflow for goal {:?}", goal);
 
         let root: JSRef<Node> = NodeCast::from_ref(root);
-        if !root.get_has_dirty_descendants() {
+        if query_type == ReflowQueryType::NoQuery && !root.get_has_dirty_descendants() {
             debug!("root has no dirty descendants; avoiding reflow");
             return
         }

components/script/layout_interface.rs

@@ -97,6 +97,7 @@ pub enum ReflowGoal {
 }
 
 /// Any query to perform with this reflow.
+#[derive(PartialEq)]
 pub enum ReflowQueryType {
     NoQuery,
     ContentBoxQuery(TrustedNodeAddress),