diff --git a/dom/animation/test/mochitest.ini b/dom/animation/test/mochitest.ini
index 5dea8ba8719..18bb7b076dd 100644
--- a/dom/animation/test/mochitest.ini
+++ b/dom/animation/test/mochitest.ini
@@ -18,3 +18,4 @@ skip-if = buildapp == 'mulet'
 [css-transitions/test_animation-target.html]
 [css-transitions/test_element-get-animation-players.html]
 skip-if = buildapp == 'mulet'
+[mozilla/test_deferred_start.html]
diff --git a/dom/animation/test/mozilla/test_deferred_start.html b/dom/animation/test/mozilla/test_deferred_start.html
new file mode 100644
index 00000000000..1795a801b7f
--- /dev/null
+++ b/dom/animation/test/mozilla/test_deferred_start.html
@@ -0,0 +1,61 @@
+<!doctype html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../testcommon.js"></script>
+<div id="log"></div>
+<style>
+@keyframes empty { }
+</style>
+<script>
+'use strict';
+
+function waitForDocLoad() {
+  return new Promise(function(resolve, reject) {
+    if (document.readyState === 'complete') {
+      resolve();
+    } else {
+      window.addEventListener('load', resolve);
+    }
+  });
+}
+
+async_test(function(t) {
+  var div = addDiv(t);
+  var cs = window.getComputedStyle(div);
+
+  // Test that empty animations actually start.
+  //
+  // Normally we tie the start of animations to when their first frame of
+  // the animation is rendered. However, for animations that don't actually
+  // trigger a paint (e.g. because they are empty, or are animating something
+  // that doesn't render or is offscreen) we want to make sure they still
+  // start.
+  //
+  // Before we start, wait for the document to finish loading. This is because
+  // during loading we will have other paint events taking place which might,
+  // by luck, happen to trigger animations that otherwise would not have been
+  // triggered, leading to false positives.
+  //
+  // As a result, it's better to wait until we have a more stable state before
+  // continuing.
+  var promiseCallbackDone = false;
+  waitForDocLoad().then(function() {
+    div.style.animation = 'empty 1000s';
+    var player = div.getAnimationPlayers()[0];
+
+    player.ready.then(function() {
+      promiseCallbackDone = true;
+    }).catch(function() {
+      assert_unreached('ready promise was rejected');
+    });
+
+  }).then(waitForFrame).then(t.step_func(function() {
+    assert_true(promiseCallbackDone,
+                'ready promise callback was called before the next'
+                + ' requestAnimationFrame callback');
+    t.done();
+  }));
+}, 'AnimationPlayer.ready is resolved for an empty animation');
+
+</script>
