Well, OK, but the problem here is that text could not only be proportionally scaled, but all the valid SVG transforms can be applied, like rotation and skew.
I agree, that my implementation is wrong concerning SVG spec bounds calculation... But it lets us to RENDER all transforms correctly, breaking layer bounds.

If you create a simple svg with transformed text, you'll easily understand what I mean.
Well, for example (sorry, I don't know, how to share files here):

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- Created with Inkscape (http://www.inkscape.org/) -->

<svg
   xmlns:dc="http://purl.org/dc/elements/1.1/"
   xmlns:cc="http://creativecommons.org/ns#"
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:svg="http://www.w3.org/2000/svg"
   xmlns="http://www.w3.org/2000/svg"
   version="1.1"
   width="744.09448"
   height="1052.3622"
   id="svg3018">
  <g
     id="layer1">
    <text
       x="14.464138"
       y="80.399139"
       transform="matrix(1.4614298,0.61852241,0.50594217,0.8983918,0,0)"
       id="text3030"
       xml:space="preserve"
       style="font-size:21.16327095px;font-style:normal;font-weight:normal;line-height:125%;letter-spacing:0px;word-spacing:0px;fill:#000000;fill-opacity:1;stroke:none;font-family:Verdana"><tspan
         x="14.464138"
         y="80.399139"
         id="tspan3032">ROTATED AND SKEWED TEXT</tspan></text>
  </g>
</svg>