<!DOCTYPE html>
<html class=reftest-wait>
<link rel="help" href="https://drafts.css-houdini.org/css-layout-api/#dom-layoutfragment-data">
<link rel="match" href="green-square-ref.html">
<meta name="assert" content="This test checks that passing something that can't be serialized to the parent triggers a fallback to block layout." />
<style>
.test {
  background: red;
  width: 100px;
}

.child {
  height: 100px;
}

@supports (display: layout(fallback-fn)) {
  .test {
    display: layout(fallback-fn);
    background: green;
  }
}
</style>
<script src="/common/reftest-wait.js"></script>
<script src="/common/worklet-reftest.js"></script>

<div class="test">
  <div class="child"></div>
</div>

<script id="code" type="text/worklet">
registerLayout('fallback-fn', class {
  async intrinsicSizes() {}
  async layout(children, edges, constraints, styleMap) {
    const childFragments = await children.map(child => child.layoutNextFragment());
    return {autoBlockSize: 0, childFragments, data: {fn: function() {}}};
  }
});
</script>

<script>
importWorkletAndTerminateTestAfterAsyncPaint(CSS.layoutWorklet, document.getElementById('code').textContent);
</script>
</html>