Please describe the problem:
Copied from Wikimedia bug report 
https://bugzilla.wikimedia.org/show_bug.cgi?id=13495

Code such as <tspan text-decoration="underline"> ... </tspan> doesn't render the underline in Mediawiki. (overline doesn't render either suggesting the problem is text-decoration generally)

Steps to reproduce:
Example:  The following SVG code (SVG attached) will render in Opera 9.5's  SVG renderer, and Adobe's SVG renderer (for IE6) as three underlined texts, but librsvg ignores the underline attribute in all 3 lines:

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" 
"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">

<svg width="500" height="450" version="1.1" xmlns="http://www.w3.org/2000/svg">
   <text style="font-size:14px;text-align:start;writing-mode:lr-tb;text-anchor:start;fill:#000000;fill-opacity:1;stroke:none;font-family:Arial">
      <tspan x="20" y='20' text-decoration="underline">Underline me!</tspan>
      <tspan x="50" y='40' style="text-decoration:underline">Underline
me!</tspan>
      <tspan x="70" y='60'>The following text is <tspan "text-decoration="underline">underlined</tspan>.</tspan>
   </text>
</svg>


Likewise the SVG demo for underlining, overlining and other text decoration at this page:
http://www.svgbasics.com/font_effects_bold.html 
if saved as an SVG file, doesnt render any of the text decoration that the tutorial says should render, although if opened in IE+Adobe or Opera 9.5 as an SVG it does. (Note - you have to remove the "contentScriptType=text/ecmascript" to get mediawiki to upload it)

Finally compare this image on Wikipedia as a WP render and when viewed native in IE+Adobe or Opera 9:

http://en.wikipedia.org/wiki/Image:BLP_flowchart_2.svg (no underlines)
and
http://upload.wikimedia.org/wikipedia/en/thumb/f/f0/BLP_flowchart_2.svg/370px-BLP_flowchart_2.svg.png (contains underlines)

Actual results:
See above - librsvg doesnt render text-decorations

Expected results:
Decorations eg underlines visible on rendered images

Does this happen every time?
Yes

Other information: