1 files changed, 13 insertions, 0 deletions
diff --git a/layout/reftests/web-animations/animation-utils.js b/layout/reftests/web-animations/animation-utils.js
new file mode 100644
index 0000000000..d34ba635a1
--- /dev/null
+++ b/layout/reftests/web-animations/animation-utils.js
@@ -0,0 +1,13 @@
+function waitForIterationChange(animation) {
+  var initialIteration = animation.effect.getComputedTiming().currentIteration;
+  return new Promise(resolve => {
+    window.requestAnimationFrame(handleFrame = () => {
+      if (animation.effect.getComputedTiming().currentIteration !=
+            initialIteration) {
+        resolve();
+      } else {
+        window.requestAnimationFrame(handleFrame);
+      }
+    });
+  });
+}