--- a/dom/animation/test/css-animations/test_animations-dynamic-changes.html
+++ b/dom/animation/test/css-animations/test_animations-dynamic-changes.html
@@ -16,25 +16,23 @@ Element.getAnimations() - Dynamic change
 <div id="log"></div>
 <script>
 'use strict';
 
 promise_test(async t => {
   const div = addDiv(t);
   div.style.animation = 'anim1 100s';
   const originalAnimation = div.getAnimations()[0];
-  let originalStartTime;
-  let originalCurrentTime;
 
   // Wait a moment so we can confirm the startTime doesn't change (and doesn't
   // simply reflect the current time).
   await originalAnimation.ready;
 
-  originalStartTime = originalAnimation.startTime;
-  originalCurrentTime = originalAnimation.currentTime;
+  const originalStartTime = originalAnimation.startTime;
+  const originalCurrentTime = originalAnimation.currentTime;
 
   // Wait a moment so we can confirm the startTime doesn't change (and
   // doesn't simply reflect the current time).
   await waitForNextFrame();
 
   div.style.animationDuration = '200s';
   const animation = div.getAnimations()[0];
   assert_equals(animation, originalAnimation,
@@ -84,27 +82,28 @@ promise_test(async t => {
 
   // Swap duration of first and second in list and prepend animation at the
   // same time
   div.style.animation = 'anim1 100s, anim1 100s, anim1 200s';
   animations = div.getAnimations();
   assert_true(animations[0] !== animation1 && animations[0] !== animation2,
               'New Animation is prepended to start of list');
   assert_equals(animations[1], animation1,
-                'First Animation is in second position after update');
+                'First animation is in second position after update');
   assert_equals(animations[2], animation2,
-                'Second Animation is in third position after update');
+                'Second animation is in third position after update');
   assert_equals(animations[1].startTime, animations[2].startTime,
-                'Old Animations have the same start time');
+                'Old animations have the same start time');
+  assert_equals(animations[0].startTime, null,
+                'New animation has a null start time');
 
-  // TODO: Check that animations[0].startTime === null
   await animations[0].ready;
 
   assert_greater_than(animations[0].startTime, animations[1].startTime,
-                      'New Animation has later start time');
+                      'New animation has later start time');
 }, 'Only the startTimes of existing animations are preserved');
 
 promise_test(async t => {
   const div = addDiv(t);
   div.style.animation = 'anim1 100s, anim1 100s';
   const secondAnimation = div.getAnimations()[1];
 
   // Wait before continuing so we can compare start times
@@ -124,32 +123,30 @@ promise_test(async t => {
                    'Remaining Animation preserves startTime');
 }, 'Animations are removed from the start of the list while preserving'
    + ' the state of existing Animations');
 
 promise_test(async t => {
   const div = addDiv(t);
   div.style.animation = 'anim1 100s';
   const firstAddedAnimation = div.getAnimations()[0];
-  let secondAddedAnimation;
-  let animations;
 
   // Wait and add second Animation
   await firstAddedAnimation.ready;
   await waitForFrame();
 
   div.style.animation = 'anim1 100s, anim1 100s';
-  secondAddedAnimation = div.getAnimations()[0];
+  const secondAddedAnimation = div.getAnimations()[0];
 
   // Wait again and add another Animation
   await secondAddedAnimation.ready;
   await waitForFrame();
 
   div.style.animation = 'anim1 100s, anim2 100s, anim1 100s';
-  animations = div.getAnimations();
+  const animations = div.getAnimations();
   assert_not_equals(firstAddedAnimation, secondAddedAnimation,
                     'New Animations are added to start of the list');
   assert_equals(animations[0], secondAddedAnimation,
                 'Second Animation remains in same position after'
                 + ' interleaving');
   assert_equals(animations[2], firstAddedAnimation,
                 'First Animation remains in same position after'
                 + ' interleaving');