This is a follow up to bug 12207. Reason to land the (part of the) split so soon is that bugs are depending on RenderSVGRoot being there, but not any other classes being split out of RenderSVGContainer.
This isn't true anymore. The code is cleanup up nowadays. And it will be even more clean once RenderSVGInnerSVGContainer is split out from RenderSVGContainer. Greetings, Niko