1 files changed, 39 insertions, 0 deletions
diff --git a/layout/reftests/reftest-sanity/reftest-no-flush.html b/layout/reftests/reftest-sanity/reftest-no-flush.html
new file mode 100644
index 0000000000..8893e6eb71
--- /dev/null
+++ b/layout/reftests/reftest-sanity/reftest-no-flush.html
@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<html class="reftest-wait reftest-no-flush">
+<style>
+html {
+  /* Suppress scrollbars to avoid periodical unthrottling for transform */
+  /* animations on the compositor. */
+  overflow: hidden;
+}
+body {
+  margin: 0px;
+  padding: 0px;
+}
+@keyframes anim {
+  0% { transform: translateX(100px); }
+  100% { transform: translateX(100px); }
+}
+#target {
+  width: 100px;
+  height: 100px;
+  position: absolute;
+  background-color: green;
+}
+</style>
+<div id="target"></div>
+<script>
+document.addEventListener('MozReftestInvalidate', () => {
+  // Set a bit longer animation delay to avoid painting the initial animation
+  // style on the main thread.
+  target.style.animation = "anim 100s 1s";
+  target.addEventListener("animationstart", () => {
+    requestAnimationFrame(() => {
+      requestAnimationFrame(() => {
+        document.documentElement.classList.remove("reftest-wait");
+      });
+    });
+  });
+}, { once: true });
+</script>
+</html>