mozilla-release/layout/reftests/outline/outline-overflow-block-float.html

<!DOCTYPE HTML>
<title>outline doesn't go around overflowing floats</title>
<style>

html, body { margin: 0; padding: 0; border: none }
html { overflow:hidden /* avoid second reflow for scrollbars */ }

body > div {
  margin: 100px;
  width: 50px; height: 50px;
  outline: 2px solid blue;
  position: relative;
}

body > div > div {
  float: left;
  width: 100px;
  height: 100px;
}

</style>
<body>
<div><div></div></div>