From 5fa9a5624798139f789b88cefeb5c4b0f7afb7d9 Mon Sep 17 00:00:00 2001
From: Cameron McCormack <cam@mcc.id.au>
Date: Tue, 4 Apr 2017 19:22:42 +0800
Subject: [PATCH] style: Don't traverse children if the root of the restyle is
 display:none.

If we append a child to a display:none element, and we use StyleNewChildren on
that parent, we should skip restyling the children.
---
 components/style/traversal.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/components/style/traversal.rs b/components/style/traversal.rs
index 37e52eafb8f..16505e71b2e 100644
--- a/components/style/traversal.rs
+++ b/components/style/traversal.rs
@@ -149,6 +149,12 @@ pub trait DomTraversal<E: TElement> : Sync {
                     -> PreTraverseToken
     {
         if traversal_flags.for_unstyled_children_only() {
+            if root.borrow_data().map_or(true, |d| d.has_styles() && d.styles().is_display_none()) {
+                return PreTraverseToken {
+                    traverse: false,
+                    unstyled_children_only: false,
+                };
+            }
             return PreTraverseToken {
                 traverse: true,
                 unstyled_children_only: true,