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diff --git a/testing/web-platform/tests/user-timing/mark-measure-feature-detection.html b/testing/web-platform/tests/user-timing/mark-measure-feature-detection.html
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+++ b/testing/web-platform/tests/user-timing/mark-measure-feature-detection.html
@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<meta charset=utf-8>
+<title>User Timing: L2 vs L3 feature detection</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+  test(() => {
+    // Feature detection for PerformanceMark.
+    assert_equals(typeof(PerformanceMark.prototype), "object");
+    // Test for UserTiming L3.
+    if (PerformanceMark.prototype.hasOwnProperty('detail')) {
+      assert_equals(typeof(performance.mark("mark")), "object",
+        "performance.mark should return an object in UserTiming L3.");
+    }
+    // Test for UserTiming L2.
+    else {
+      assert_equals(typeof(performance.mark("mark")), "undefined",
+        "performance.mark should be void in UserTiming L2.");
+    }
+  }, "Test PerformanceMark existence and feature detection");
+
+  test(() => {
+    // Feature detection for PerformanceMeasure.
+    assert_equals(typeof(PerformanceMeasure.prototype), "object");
+    // Test for UserTiming L3.
+    if (PerformanceMeasure.prototype.hasOwnProperty('detail')) {
+      assert_equals(typeof(performance.measure("measure")), "object",
+        "performance.measure should return an object in UserTiming L3.");
+    }
+    // Test for UserTiming L2.
+    else {
+      assert_equals(typeof(performance.measure("measure")), "undefined",
+        "performance.measure should be void in UserTiming L2.");
+    }
+  }, "Test PerformanceMeasure existence and feature detection");
+</script>