chromium/third_party/blink/manual_tests/frame-hover.html

<body>
<p style="height: 50px;">Move the mouse pointer into the yellow box, then directly into the green box, then out of both boxes. No red or cyan should remain, only yellow and green.</p>
<iframe src="resources/hover-subframe-1.html" frameborder="0" height="300" scrolling="no" width="200"></iframe><iframe src="resources/hover-subframe-2.html" frameborder="0" height="300" scrolling="no" width="200"></iframe>
</body>
</html>