1 files changed, 58 insertions, 0 deletions
diff --git a/layout/reftests/transform/partial-prerender-translate-5.html b/layout/reftests/transform/partial-prerender-translate-5.html
new file mode 100644
index 0000000000..6225b7de25
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+++ b/layout/reftests/transform/partial-prerender-translate-5.html
@@ -0,0 +1,58 @@
+<!DOCTYPE html>
+<html class="reftest-wait reftest-no-flush"
+      reftest-async-scroll
+      reftest-displayport-x="0" reftest-displayport-y="0"
+      reftest-displayport-w="800" reftest-displayport-h="2000"
+      reftest-async-scroll-x="0" reftest-async-scroll-y="1000">
+<meta name="viewport" content="width=device-width,minimum-scale=1,initial-scale=1">
+<!--
+  A test that a partial pre-rendered transform animation is in a position:fixed
+  layer.
+  -->
+<style>
+html {
+  overflow-x: hidden;
+}
+body {
+  margin: 0px;
+  padding: 0px;
+}
+@keyframes anim {
+  to { transform: translateY(-500px); }
+}
+#target {
+  width: 800px;
+  height: 1600px;
+  transform: translateY(-400px);
+}
+</style>
+<div style="width: 800px; height: 2000px"><!-- spacer --></div>
+<div style="position: fixed; top: 400px">
+  <div id="target">
+    <!--
+      Put an SVG element so that the transform display item has a blob on
+      WebRender which means this test properly fails without the proper fix.
+      -->
+    <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 800 1600">
+      <rect fill="green" y="0"    width="800" height="1000"></rect>
+      <rect fill="blue"  y="1000" width="800" height="125"></rect>
+      <rect fill="red"   y="1125" width="800" height="875"></rect>
+    </svg>
+  </div>
+</div>
+<script>
+document.addEventListener("MozReftestInvalidate", () => {
+  target.style.animation = "anim 100s 1s step-start";
+  target.addEventListener("animationstart", () => {
+    // animtionstart event is fired just before requestAnimationFrame callbacks,
+    // so we need to wait two rAF to make sure the initial animation value is
+    // composited on the compositor.
+    requestAnimationFrame(() => {
+      requestAnimationFrame(() => {
+        document.documentElement.classList.remove("reftest-wait");
+      });
+    });
+  });
+}, { once: true });
+</script>
+</html>