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diff --git a/layout/reftests/css-animations/containing-block-on-visibility-hidden.html b/layout/reftests/css-animations/containing-block-on-visibility-hidden.html
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+++ b/layout/reftests/css-animations/containing-block-on-visibility-hidden.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<title>
+Transform animation generates a containing block for fixed-pos descendants
+even if the animation value is 'transform:none'
+</title>
+<style>
+#parent {
+  visibility: hidden;
+  animation: anim 100s step-end;
+}
+
+#fixed {
+  position: fixed;
+  background-color: green;
+  height: 100px;
+  width: 100px;
+}
+
+#scroll {
+  overflow-y: scroll;
+  overflow-x: hidden;
+  height: 80px;
+  width: 100px;
+}
+@keyframes anim {
+  0% { transform: none; }
+  100% { transform: translateX(0px); }
+}
+</style>
+<div id="scroll">
+  <div id="parent">
+    <div id="fixed"></div>
+  </div>
+</div>