From a6ceafe3daaea3d207a3cbc6e5c4944c4d8f00d9 Mon Sep 17 00:00:00 2001
From: KuoE0 <kuoe0.tw@gmail.com>
Date: Mon, 14 Aug 2017 15:09:24 +0800
Subject: [PATCH] Make emtpy rule can be inserted into rule tree

---
 components/style/rule_tree/mod.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/components/style/rule_tree/mod.rs b/components/style/rule_tree/mod.rs
index ff511a2a583..1b1062d255a 100644
--- a/components/style/rule_tree/mod.rs
+++ b/components/style/rule_tree/mod.rs
@@ -210,7 +210,10 @@ impl RuleTree {
                     _ => {},
                 };
             }
-            if any_normal {
+            // We really want to ensure empty rule nodes appear in the rule tree for
+            // devtools, this condition ensures that if we find an empty rule node, we
+            // insert it at the normal level.
+            if any_normal || !any_important {
                 if matches!(level, Transitions) && found_important {
                     // There can be at most one transition, and it will come at
                     // the end of the iterator. Stash it and apply it after