mozilla-release/layout/reftests/css-transitions/transitions-inline-rewrap-2.html

<html class="reftest-wait">
<title>Test for CSS transitions and re-wrapping of inlines</title>
<style type="text/css">
#test { transition: 20ms color linear 0; }
</style>
<script type="text/javascript">

window.onload = run;

function run() {
  var test = document.getElementById("test");
  var unused = test.offsetWidth;
  unused = getComputedStyle(test, "").color;
  test.style.color = "green";
  unused = test.offsetWidth;
  unused = getComputedStyle(test, "").color;
  test.parentNode.style.width = "3em";
  unused = test.offsetWidth;
  unused = getComputedStyle(test, "").color;
  setTimeout(step2, 100); // give transition time to run
}
function step2() {
  document.documentElement.removeAttribute("class");
}

</script>
<div style="width: 50em">
<span id="test" style="color: red">
This is some text with a transition.
</span>
</div>