LayoutTests/fast/block/percent-margin-start-end-with-floats-expected.html

<style>
div {
  width: 50px;
  height: 50px;
}

.left {
  background-color: green;
}
.right {
  position: relative;
  top: -50px;
  left: 100px;
  background-color: blue;
}
</style>
<div class=left></div><div class=right></div>