From 40dd807df399399f2d41ddebc1f1ac668ac4fc8f Mon Sep 17 00:00:00 2001
From: Boris Zbarsky <bzbarsky@mit.edu>
Date: Mon, 26 Jun 2017 23:24:56 -0700
Subject: [PATCH] Assert that compute_style_difference is only called with
 eager pseudos.

Gecko bug 1324618 part 3: https://bugzilla.mozilla.org/show_bug.cgi?id=1324618
---
 components/style/matching.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/components/style/matching.rs b/components/style/matching.rs
index dd351c08c92..542bd512a0b 100644
--- a/components/style/matching.rs
+++ b/components/style/matching.rs
@@ -1478,6 +1478,7 @@ pub trait MatchMethods : TElement {
                                 pseudo: Option<&PseudoElement>)
                                 -> StyleDifference
     {
+        debug_assert!(pseudo.map_or(true, |p| p.is_eager()));
         if let Some(source) = self.existing_style_for_restyle_damage(old_values, pseudo) {
             return RestyleDamage::compute_style_difference(source, new_values)
         }