From f1bd968c5c9bf7c1c7183d51d6289e8eeb366059 Mon Sep 17 00:00:00 2001
From: Johann Hofmann <jhofmann@mozilla.com>
Date: Thu, 16 Aug 2018 18:30:53 +0000
Subject: [PATCH] Bug 1478637 - Avoid sync style flushes when cancelling the
 shield animation in the identity block. r=mconley

Differential Revision: https://phabricator.services.mozilla.com/D3449

--HG--
extra : moz-landing-system : lando
---
 browser/base/content/browser-contentblocking.js | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/browser/base/content/browser-contentblocking.js b/browser/base/content/browser-contentblocking.js
index f6522b696f32..005042f9d2ea 100644
--- a/browser/base/content/browser-contentblocking.js
+++ b/browser/base/content/browser-contentblocking.js
@@ -379,11 +379,18 @@ var ContentBlocking = {
   },
 
   cancelAnimation() {
-    let iconAnimation = this.animatedIcon.getAnimations()[0];
-    if (iconAnimation && iconAnimation.currentTime) {
-      iconAnimation.cancel();
+    if (!this.iconBox.hasAttribute("animate")) {
+      return;
     }
-    this.iconBox.removeAttribute("animate");
+
+    window.promiseDocumentFlushed(() => {
+      return this.animatedIcon.getAnimations()[0];
+    }).then(iconAnimation => {
+      if (iconAnimation && iconAnimation.currentTime) {
+        iconAnimation.cancel();
+      }
+      this.iconBox.removeAttribute("animate");
+    });
   },
 
   onSecurityChange(state, webProgress, isSimulated) {