1 files changed, 53 insertions, 0 deletions
diff --git a/layout/reftests/transform/partial-prerender-translate-7.html b/layout/reftests/transform/partial-prerender-translate-7.html
new file mode 100644
index 0000000000..06c26c66fb
--- /dev/null
+++ b/layout/reftests/transform/partial-prerender-translate-7.html
@@ -0,0 +1,53 @@
+<!DOCTYPE html>
+<html class="reftest-wait reftest-no-flush">
+<meta name="viewport" content="width=device-width,minimum-scale=1,initial-scale=1">
+<!--
+  Another variant of partial-prerender-translate-2.html, but the transform
+  animation is scaled by the parent element.
+  -->
+<style>
+html {
+  overflow: hidden;
+}
+body {
+  margin: 0px;
+  padding: 0px;
+}
+@keyframes anim {
+  /* translate to a position where the left edge of partial pre-rendered on */
+  /* the left edge of the viewport. */
+  0% { transform: translateX(-649px); }
+  100% { transform: translateX(-2000px); }
+}
+#target {
+  width: 4000px;
+  height: 2000px;
+  position: absolute;
+  transform: translateX(0);
+}
+</style>
+<div style="transform: scale(0.5); transform-origin: 0 0">
+  <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 4000 2000">
+      <rect fill="green" x="0" width="2250" height="2000"></rect>
+      <rect fill="red" x="2250" width="1750" height="2000"></rect>
+    </svg>
+  </div>
+</div>
+<script>
+document.addEventListener("MozReftestInvalidate", () => {
+  target.style.animation = "anim 10s 1s";
+  target.addEventListener("animationstart", () => {
+    // Wait a second to make sure the animation gets stucked (i.e. jank) at the
+    // boundary (650px).
+    setTimeout(() => {
+      document.documentElement.classList.remove("reftest-wait");
+    }, 1000);
+  });
+}, { once: true });
+</script>
+</html>