nsSVGUtils::ToAppPixelRect rounds CSS px before scaling them, which means we get inaccurate results. Unfortunately we have tests that contain off numbers to compensate, but these inaccuracies are exaggerated even further by the kill-covered-regions patches in bug 614732, causing those tests to fail with those patches.
In principle nsSVGUtils::ToAppPixelRect duplicates nsLayoutUtils::RoundGfxRectToAppRect, and the latter rounds properly making it more accurate. Switching to RoundGfxRectToAppRect gets me part way to solving the failures that occur with the kill-covered-regions patches in bug 614732.
Created attachment 595918 [details] [diff] [review]
Comment on attachment 595918 [details] [diff] [review]
Actually, there's no reason to put this in roc's path (I was just in "it's display list stuff" mode).