LayoutTests/animations/animation-border-overflow.html

<html>
<head>
<title>Unfilled Animation Test</title>
<style type="text/css" media="screen">
#box {
    height: 100px;
    width: 100px;
    border-top-width: 300px;
    border-style: solid;
    -webkit-animation-duration: 1s;
    -webkit-animation-timing-function: ease-in-out;
    -webkit-animation-name: "anim";
}
@-webkit-keyframes "anim" {
    from { border-top-width: 200px; }
    to   { border-top-width: 0px; }
}

</style>
    <script src="resources/animation-test-helpers.js" type="text/javascript" charset="utf-8"></script>
    <script type="text/javascript" charset="utf-8">
    if (window.testRunner)
        testRunner.dumpAsText();

    const expectedValues = [
      // [animation-name, time, element-id, property, expected-value, tolerance]
      ["anim", 0.1, "box", "border-top-width", 200, 20],
    ];

    runAnimationTest(expectedValues);
    </script>
</head>
<body>
This test performs an animation of the border-top-width property from a given value to 0. It tests if an intermediate value is correct.
<div id="box">
</div>
<div id="result">
</div>
</body>
</html>