Now that we are not calling GetCanvasTM inside UpdateFontSizeScaleFactor, we don't have to try to avoid calling in to nsSVGMarkerFrame::GetCanvasTM when it has no marked frame (when it would crash). Also, I don't think it's correct to be using FOR_PAINTING and FOR_HIT_TESTING anyway, because we want to work out the size of the text as it will be rendered (for displayed SVG text at least), and when SVG display lists are enabled, GetCanvasTM(FOR_{PAINTING,HIT_TESTING}) will not return a matrix that captures the transforms right up the tree.