<!DOCTYPE html>
<script>
function test()
{
if (!window.testRunner || !window.internals)
return;
testRunner.dumpAsText();
document.body.offsetTop;
internals.startTrackingRepaints(document);
document.getElementById('left').style.top = '400px';
document.getElementById('right').style.top = '400px';
document.body.offsetTop;
var layerTree = internals.layerTreeAsText(document, internals.LAYER_TREE_INCLUDES_INVALIDATIONS);
internals.stopTrackingRepaints(document);
document.getElementById('result').textContent = layerTree.indexOf('repaint') == -1 ? 'SUCCESS' : 'FAIL';
}
window.onload = test;
</script>
<style>
#left, #right {
position: absolute;
top: 200px;
backface-visibility: hidden;
}
#left {
left: 0px;
}
#right {
right: 0px;
}
</style>
There should be no repaint when the divs are moved vertically.
<div id="left">Left</div>
<div id="right">Right</div>
<pre id="result"></pre>