The SVG file at http://gunther.ne.keryx.se/ie8-metatag.svg renders like this in Firefox on Linux (apparently): http://gunther.ne.keryx.se/ie8-metatag.png
I don't know what's wrong or as a consequence, if this is a duplicate bug. And it's the middle of the night and I'm too tired to check.
Created attachment 18915 [details]
Reduction to an ellipse with text
Confirmed in r29955.
Although it does not look the same exactly as in Firefox, I think it is a similar issue, namely kerning. When Gecko recently landed a fix for kerning my SVG rendered perfectly.
I have just updated the status page: http://keryx.se/dev/svg/geckobug-08-01/ From there you may also see my original SVG file at http://keryx.se/dev/svg/geckobug-08-01/ie8-metatag.html The URL above will be removed shortly.
The patch on bug 12448 fixes this problem. Thanks a lot for the testcase, I've integrated it in my patch.
*** This bug has been marked as a duplicate of bug 12448 ***