From c05e45fdd1649163f8e558a64c84629f86866bbc Mon Sep 17 00:00:00 2001
From: Cameron McCormack <cam@mcc.id.au>
Date: Thu, 12 Oct 2017 09:13:38 +0800
Subject: [PATCH] style: Skip custom properties comparison if other inherited
 properties changed.

---
 components/style/gecko/restyle_damage.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/components/style/gecko/restyle_damage.rs b/components/style/gecko/restyle_damage.rs
index f325e7916ed..f8a43e8b7ea 100644
--- a/components/style/gecko/restyle_damage.rs
+++ b/components/style/gecko/restyle_damage.rs
@@ -57,6 +57,16 @@ impl GeckoRestyleDamage {
                 &mut reset_only,
             )
         };
+        if reset_only &&
+           old_style.custom_properties() != new_style.custom_properties() {
+            // The Gecko_CalcStyleDifference call only checks the non-custom
+            // property structs, so we check the custom properties here. Since
+            // they generate no damage themselves, we can skip this check if we
+            // already know we had some inherited (regular) property
+            // differences.
+            any_style_changed = true;
+            reset_only = false;
+        }
         let change = if any_style_changed {
             StyleChange::Changed { reset_only }
         } else {