Couple of bugs in Chrome

Finally got round to reporting a couple of annoying bugs in Chrome (well, actually in WebKit I suppose as they seem to also occur in Safari) with regards to SVG use.

 Test cases: http://www.mysparebrain.com/svgbug.html

 Logged as http://crbug.com/98391 and http://crbug.com/98392

Here's hoping I can get rid of my nasty hack-arounds that force redraws at appropriate times...