Most of the SVGs of this page don't test at all the described features, they're just PNGs or JPEGs embedded in SVG files. The author didn't even open its SVGs generated by Illustrator: a drop shadow in Illustrator does not mean a drop shadow in the generated SVG!
For example, look at the source of the "mesh" test, it's a beautiful embedded base64 PNG: http://voormedia.com/blog/2012/10/creating-svg-vector-graphi...