--- a/testing/web-platform/tests/web-animations/keyframe-effect/effect-easing.html
+++ b/testing/web-platform/tests/web-animations/keyframe-effect/effect-easing.html
@@ -430,17 +430,17 @@ test(function(t) {
   });
   assert_style_left_at(anim, 1000, function(x) {
     return easing(easing(x))
   });
 }, 'effect easing which produces negative values and the tangent on ' +
    'the lower boundary is infinity with keyframe easing producing ' +
    'negative values');
 
-var gStepStartEasingTests = [
+var gStepTimingFunctionTests = [
   {
     description: 'Test bounds point of step-start easing',
     keyframe:   [ { width: '0px' },
                   { width: '100px' } ],
     effect:     {
                   delay: 1000,
                   duration: 1000,
                   fill: 'both',
@@ -643,19 +643,66 @@ var gStepStartEasingTests = [
                   { currentTime: 999,  progress: 0,     width: '0px' },
                   { currentTime: 1000, progress: 0,     width: '50px' },
                   { currentTime: 1499, progress: 0.499, width: '50px' },
                   { currentTime: 1500, progress: 0.5,   width: '100px' },
                   { currentTime: 2000, progress: 1,     width: '100px' },
                   { currentTime: 2500, progress: 1,     width: '100px' }
                 ]
   },
+  {
+    description: 'Test bounds point of step-end easing ' +
+                 'with iterationStart and delay',
+    keyframe:   [ { width: '0px' },
+                  { width: '100px' } ],
+    effect:     {
+                  duration: 1000,
+                  fill: 'both',
+                  delay: 1000,
+                  iterationStart: 0.5,
+                  easing: 'steps(2, end)'
+                },
+    conditions: [
+                  { currentTime: 0,    progress: 0 },
+                  { currentTime: 999,  progress: 0 },
+                  { currentTime: 1000, progress: 0.5 },
+                  { currentTime: 1499, progress: 0.5 },
+                  { currentTime: 1500, progress: 0 },
+                  { currentTime: 1999, progress: 0 },
+                  { currentTime: 2000, progress: 0.5 },
+                  { currentTime: 2500, progress: 0.5 }
+                ]
+  },
+  {
+    description: 'Test bounds point of step-end easing ' +
+                 'with iterationStart not at a transition point',
+    keyframe:   [ { width: '0px' },
+                  { width: '100px' } ],
+    effect:     {
+                  delay: 1000,
+                  duration: 1000,
+                  fill: 'both',
+                  iterationStart: 0.75,
+                  easing: 'steps(2, end)'
+                },
+    conditions: [
+                  { currentTime: 0,    progress: 0.5 },
+                  { currentTime: 999,  progress: 0.5 },
+                  { currentTime: 1000, progress: 0.5 },
+                  { currentTime: 1249, progress: 0.5 },
+                  { currentTime: 1250, progress: 0 },
+                  { currentTime: 1749, progress: 0 },
+                  { currentTime: 1750, progress: 0.5 },
+                  { currentTime: 2000, progress: 0.5 },
+                  { currentTime: 2500, progress: 0.5 },
+                ]
+  }
 ]
 
-gStepStartEasingTests.forEach(function(options) {
+gStepTimingFunctionTests.forEach(function(options) {
   test(function(t) {
     var target = createDiv(t);
     var animation = target.animate(options.keyframe, options.effect);
     options.conditions.forEach(function(condition) {
       animation.currentTime = condition.currentTime;
       if (typeof condition.progress !== 'undefined') {
         assert_equals(animation.effect.getComputedTiming().progress,
                       condition.progress,