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Test Info: Warnings

<!DOCTYPE html>
<title>Layout Instability: shift with counterscroll not counted, with 2 scrollers</title>
<link rel="help" href="https://wicg.github.io/layout-instability/" />
<style>
.scroller {
overflow: scroll;
position: absolute;
left: 20px;
top: 20px;
width: 200px;
height: 200px;
}
.content {
width: 170px;
height: 600px;
}
.changer {
position: relative;
background: yellow;
left: 10px;
top: 100px;
width: 150px;
height: 150px;
}
</style>
<div id="scroller1" class="scroller">
<div class="content">
<div id="changer1" class="changer"></div>
</div>
</div>
<div id="scroller2" class="scroller">
<div class="content">
<div id="changer2" class="changer"></div>
</div>
</div>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/util.js"></script>
<script>
promise_test(async () => {
const watcher = new ScoreWatcher;
// Wait for the initial render to complete.
await waitForAnimationFrames(2);
// Top goes from 100 to 200. scroll by 100 to counter it.
changer1.style.top = "200px";
scroller1.scrollTop = 100;
// Top goes from 100 to 300. scroll by 200 to counter it.
changer2.style.top = "300px";
scroller2.scrollTop = 200;
await waitForAnimationFrames(3);
assert_equals(watcher.score, 0);
}, "Shift with counterscroll not counted, with 2 scrollers.");
</script>