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diff --git a/layout/reftests/transform/partial-prerender-expansion-with-resolution-1.html b/layout/reftests/transform/partial-prerender-expansion-with-resolution-1.html
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+++ b/layout/reftests/transform/partial-prerender-expansion-with-resolution-1.html
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+<!DOCTYPE html>
+<html class="reftest-wait reftest-no-flush" reftest-resolution="0.5">
+<meta name="viewport" content="width=device-width,minimum-scale=0.5,initial-scale=1">
+<!--
+  A test for a partial pre-rendered transform animation with <1.0 resolution.
+  -->
+<style>
+html {
+  scrollbar-width: none;
+}
+body {
+  margin: 0px;
+  padding: 0px;
+}
+@keyframes anim {
+  /* The reftest window size is (800x1000) and it's scaled by 0.5             */
+  /* (= 1600x2000), which means the partial pre-render size is (2250x2250) so */
+  /* move to a position inside the pre-render area and away from the          */
+  /* pre-render right edge, translateX(-650px), so that we can avoid blurry   */
+  /* edges in comparison with the reference.                                  */
+  to { transform: translateX(-400px); }
+}
+#target {
+  width: 4000px;
+  height: 4000px;
+  position: absolute;
+  transform: translateX(0px);
+}
+</style>
+<div id="target">
+  <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 4000 4000">
+    <rect fill="green" x="0"    width="1600" height="4000"></rect>
+    <rect fill="blue"  x="1600" width="650"  height="4000"></rect>
+    <rect fill="red"   x="2250" width="1750" height="4000"></rect>
+  </svg>
+</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>