Percentage in 'y' not taken into account properly.

[Arnaud-F]

Hi,

this simple SVG renders properly in IE/Chrome but not when converting using the library :

<?xml version="1.0" encoding="utf-8"?>
<svg xmlns="http://www.w3.org/2000/svg" width="600" height="200" viewbox="0 0 600 200">
 <style type="text/css"><![CDATA[ rect { fill: white; stroke: black; } ]]></style>
 <g>
  <rect y="00%" width="200" height="20%" />
  <rect y="20%" width="200" height="20%" />
  <rect y="40%" width="200" height="20%" />
  <rect y="60%" width="200" height="20%" />
  <rect y="80%" width="200" height="20%" />
 </g>
</svg>