mozilla-release/layout/reftests/text-overflow/vertical-decorations-2.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<style>
div {
  font: 25px monospace;
  white-space: pre;
  overflow: hidden;
  text-overflow: ellipsis;
  border: 1px solid gray;
  padding: 5px;
  display: inline-block;
  vertical-align: top;
}
span {
  text-decoration: overline;
}
.vlr {
  writing-mode: vertical-lr;
  text-orientation: sideways-right;
  height: 10ch;
}
</style>
</head>

<body>
<div class="vlr"><span>abcdefghijklm</span></div>
</body>
</html>