--- a/testing/web-platform/tests/web-animations/resources/keyframe-utils.js
+++ b/testing/web-platform/tests/web-animations/resources/keyframe-utils.js
@@ -172,16 +172,22 @@ var gPropertyIndexedKeyframesTests = [
                left: "10px" }] },
   { desc:   "a one property two value property-indexed keyframes specification"
             + " where the second value is invalid",
     input:  { left: ["10px", "invalid"] },
     output: [{ offset: null, computedOffset: 0, easing: "linear",
                left: "10px" },
              { offset: null, computedOffset: 1, easing: "linear",
                left: "invalid" }] },
+  { desc:   "specified easing property-indexed keyframes specification",
+    input:  { left: ["10px", "20px"], easing: "step-start" },
+    output: [{ offset: null, computedOffset: 0, easing: "step-start",
+               left: "10px" },
+             { offset: null, computedOffset: 1, easing: "step-start",
+               left: "20px" }] },
 ];
 
 var gKeyframeSequenceTests = [
   { desc:   "a one property one keyframe sequence",
     input:  [{ offset: 1, left: "10px" }],
     output: [{ offset: null, computedOffset: 1, easing: "linear",
                left: "10px" }] },
   { desc:   "a one property two keyframe sequence",