<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Attributes of boundary events during dragging mouse</title>
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script src=/resources/testdriver.js></script>
<script src=/resources/testdriver-actions.js></script>
<script src=/resources/testdriver-vendor.js></script>
<style>
div.target {
  margin: 0;
  width: 100%;
  height: 16px;
}
</style>
<script>
"use strict";

addEventListener("load", () => {
 