LayoutTests/tiled-drawing/tile-coverage-iframe-to-zero-coverage.html - WebKit - Git at Google

 <!DOCTYPE html>

 <html>
 <head>
     <style>
         body {
             height: 5000px;
         }
         iframe {
             height: 400px;
             width: 800px;
             border: 5px solid black;
             box-shadow: 0 0 5px black;
             padding: 20px;
         }
     </style>
     <script>
         if (window.testRunner) {
             testRunner.dumpAsText();
             testRunner.waitUntilDone();
         }

         function doTest()
         {
             setTimeout(function() {
                 window.scrollTo(0, 3000);
 				internals.layerTreeAsText(subframe.contentDocument);
                 if (window.internals) {
                     document.getElementById('layers').innerText = internals.layerTreeAsText(document,
                         internals.LAYER_TREE_INCLUDES_VISIBLE_RECTS | internals.LAYER_TREE_INCLUDES_TILE_CACHES);
                 }
                 if (window.testRunner)
                     testRunner.notifyDone();
             }, 0);
         }
         window.addEventListener('load', doTest, false);
     </script>
 </head>
 <body>

 <iframe id="subframe" scrolling="no" srcdoc="<div style='width: 2500px; height: 200px; background-color: silver; will-change: transform'>Stuff here</div>"></iframe>
 <pre id="layers">Layer tree goes here</p>
 </body>
 </html>
	<!DOCTYPE html>

	<html>
	<head>
	<style>
	body {
	height: 5000px;
	}
	iframe {
	height: 400px;
	width: 800px;
	border: 5px solid black;
	box-shadow: 0 0 5px black;
	padding: 20px;
	}
	</style>
	<script>
	if (window.testRunner) {
	testRunner.dumpAsText();
	testRunner.waitUntilDone();
	}

	function doTest()
	{
	setTimeout(function() {
	window.scrollTo(0, 3000);
	internals.layerTreeAsText(subframe.contentDocument);
	if (window.internals) {
	document.getElementById('layers').innerText = internals.layerTreeAsText(document,
	internals.LAYER_TREE_INCLUDES_VISIBLE_RECTS \| internals.LAYER_TREE_INCLUDES_TILE_CACHES);
	}
	if (window.testRunner)
	testRunner.notifyDone();
	}, 0);
	}
	window.addEventListener('load', doTest, false);
	</script>
	</head>
	<body>

	<iframe id="subframe" scrolling="no" srcdoc="<div style='width: 2500px; height: 200px; background-color: silver; will-change: transform'>Stuff here</div>"></iframe>
	<pre id="layers">Layer tree goes here</p>
	</body>
	</html>