viewport.html

<!DOCTYPE html>
<head>
	<LINK href="stylesheets/github-dark.css" rel="stylesheet" type="text/css">
	<LINK href="stylesheets/github-light.css" rel="stylesheet" type="text/css">
	<LINK href="stylesheets/main.css" rel="stylesheet" type="text/css">
	<LINK href="stylesheets/normalize.css" rel="stylesheet" type="text/css">
	<LINK href="stylesheets/print.css" rel="stylesheet" type="text/css">
	<LINK href="stylesheets/styles.css" rel="stylesheet" type="text/css">
</head>
<body>
	<div style="width: 100%">
	   <img style="width: 100px; height: 100px" src="large.jpg"/>
	</div>
	<div style="height: 99999px; width: 100%" id="view_div"></div>
	<div style="width: 100%">
	  <img style="width: 100px; height: 100px" src="large_out_of_viewport.jpg">
	</div>
	<script>
	document.body.offsetTop; // Force a layout.
	</script>

	<script>
	document.body.offsetTop; // Force a layout.
	</script>
</body>
</html>