SVG rendering issue with Webkit

Open the attached html file with Qt Fancy Browser example application and compare the web page to opening the html file with some browser e.g. Chrome.

The webpage loads SVGs and in Chrome you'll see four circles.
Two side by side and two overlapping. One of each pair is light green with a circle gradient and the other is dark dreen.

In Fancy Browser just the upper left circle renders, sometimes dark green and sometimes light green, but without any gradient effect. In Qt 5.3 it might also cause a crash on Windows.