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Test Info: Warnings

<!DOCTYPE html>
<title>Layout Instability: parent (with overflow:hidden) and child moved together</title>
<link rel="help" href="https://wicg.github.io/layout-instability/" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/util.js"></script>
<div id="parent" style="position: relative; width: 200px; height: 200px;
border: 50px solid blue; overflow: hidden">
<div id="child" style="width: 400px; height: 400px; background: blue"></div>
</div>
<script>
promise_test(async () => {
const watcher = new ScoreWatcher;
// Wait for the initial render to complete.
await waitForAnimationFrames(2);
// Modify the position of the div.
const parent = document.querySelector("#parent");
parent.style.top = '100px';
// Only the parent area should be reported.
const expectedScore = computeExpectedScore(300 * (300 + 100), 100);
// Observer fires after the frame is painted.
assert_equals(watcher.score, 0);
await watcher.promise;
assert_equals(watcher.score, expectedScore);
}, 'Parent (with overflow:hidden) and child moved together.');
</script>