LayoutTests/fast/overflow/vertical-overflow-with-offset.html

<style>
#container {
  position: absolute;
  top: 100px;
  left: 100px;

  width: 100px;
  height: 100px;
  overflow: hidden;

  background-color: green;
}

#child {
  width: 10px;
  height: 10px;
  background-color: blue;
}
</style>
<div id=container><div id=child></div></div>
<pre id=result></pre>
<script>
if (window.testRunner) {
  testRunner.dumpAsText();
  testRunner.waitUntilDone();
}

function overflowChanged(event) {
  result.innerText = !event.verticalOverflow ? "PASS" : "FAIL";
  if (window.testRunner)
    testRunner.notifyDone();
}
container.addEventListener('overflowchanged', overflowChanged, false);

document.body.offsetHeight;
// This should not trigger vertical overflow change.
child.style.width = "120px";
</script>