LayoutTests/fast/multicol/nested-spanner-assert.html

<style>
.multi-column {
  column-count: 2;
}
.absolute {
  position: absolute;
}
.spanner {
  column-span: all;
}
</style>
PASS if no crash or assert.
<div class=multi-column>
  <div id=go_inflow class="absolute spanner">
    <div id=become_spanner></div>
  </div>
</div>
<script>
if (window.testRunner)
  testRunner.dumpAsText();
document.body.offsetHeight;
go_inflow.classList.remove("absolute");
document.body.offsetHeight;
become_spanner.classList.add("spanner");
</script>