Webkit apply text-underline even when there is no text

Webkit apply the CSS property text-underline even when there is no text.

For example, go to http://www.linuxcertif.com/metanews/tout-en/ and move the mouse cursor to one of the little green plus sign. With Qt Webkit, an underscore is visible. The html code to show this image is:

<a href="#">
<span class="action extend"/>
</a>

With the CSS:

#content li.feedentry span.action {metanews.css (line 27)
background-repeat:no-repeat;
border:0pt none;
height:17px;
margin-bottom:-3px;
margin-left:5px;
margin-right:5px;
padding-right:17px;
width:17px;
}

Since there is no text in the span, no decoration is expected.