src/third_party/web_platform_tests/dom/events/Event-constants.html

<!doctype html>
<title>Event constants</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../constants.js"></script>
<div id="log"></div>
<script>
var objects;
setup(function() {
  objects = [
    [Event, "Event interface object"],
    [Event.prototype, "Event prototype object"],
    [document.createEvent("Event"), "Event object"],
    [document.createEvent("CustomEvent"), "CustomEvent object"]
  ]
})
testConstants(objects, [
  ["NONE", 0],
  ["CAPTURING_PHASE", 1],
  ["AT_TARGET", 2],
  ["BUBBLING_PHASE", 3]
], "eventPhase")
</script>