exbox horizontal" style="-webkit-align-content: stretch; height: 30px">
  <div data-offset-x="0" data-offset-y="0" data-expected-height="20"></div>
  <div data-offset-x="100" data-offset-y="0" data-expected-height="20"></div>
  <div data-offset-x="0" data-offset-y="20" data-expected-height="20"></div>
  <div data-offset-x="0" data-offset-y="40" data-expected-height="20"></div>
</div>

<!-- 0 lines should not crash. -->
<div data-expected-height="30" class="flexbox horizontal" style="-webkit-align-content: s