1 files changed, 38 insertions, 0 deletions
diff --git a/layout/reftests/web-animations/stacking-context-opacity-changing-target-in-delay.html b/layout/reftests/web-animations/stacking-context-opacity-changing-target-in-delay.html
new file mode 100644
index 000000000..7a6b30d79
--- /dev/null
+++ b/layout/reftests/web-animations/stacking-context-opacity-changing-target-in-delay.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<html class="reftest-wait">
+<title>
+Changing target to an element that does not override opacity animations
+creates a stacking context even if the animation is delay phase
+</title>
+<style>
+span {
+  height: 100px;
+  width: 100px;
+  position: fixed;
+  background: green;
+  top: 50px;
+}
+#first {
+  width: 100px; height: 100px;
+  background: blue;
+  opacity: 1 ! important;
+}
+#second {
+  width: 100px; height: 100px;
+  background: blue;
+}
+</style>
+<span></span>
+<div id="first"></div>
+<div id="second"></div>
+<script>
+  var anim = document.getElementById("first")
+    .animate({ opacity: [0, 1] },
+             { delay: 100000, duration: 100000 });
+  anim.ready.then(function() {
+    anim.effect.target = document.getElementById("second");
+    requestAnimationFrame(function() {
+      document.documentElement.classList.remove("reftest-wait");
+    });
+  });
+</script>