Along the lines of bug 769103, SVG patterns don't account for transforms that are already applied to the gfxContext that is being painting to. For elements that are under a CSS transform that's scales the element up, this means that we create surfaces that are too small (or, more to the point, surfaces that don't have enough resolution) when creating patterns. As a result, the more the element is scaled up, the more pixelated the pattern becomes.
This isn't generally a problem for SVG, since the transforms aren't accumulated on the gfxMatrix as we descend down the tree. However, when switching to display list painting of SVG, we do accumulate the transforms as we descend the tree, and this bug causes various SVG reftests to fail.
Created attachment 641854 [details] [diff] [review]