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Test Info: Warnings

<!DOCTYPE html>
<title>Layout Instability: shift accompanied by body display change</title>
<link rel="help" href="https://wicg.github.io/layout-instability/" />
<style>
body { margin: 0; }
#cont {
background: white;
width: 300px;
height: 200px;
}
#ch {
background: blue;
position: relative;
width: 300px;
height: 100px;
top: 100px;
}
</style>
<style id="s"></style>
<div id="cont">
<div id="ch"></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;
await waitForAnimationFrames(2);
document.querySelector("#s").innerHTML = `
body {
display: flex;
flex-direction: column;
}
#ch { top: 0; }
`;
// An element of size (300 x 100) has shifted by 100px.
const expectedScore = computeExpectedScore(300 * (100 + 100), 100);
// Observer fires after the frame is painted.
assert_equals(watcher.score, 0);
await watcher.promise;
assert_equals(watcher.score, expectedScore);
}, 'Shift accompanied by body display change.');
</script>