NS_ENSURE_ARG(matrix);
if (!matrix) return NS_ERROR_DOM_SVG_WRONG_TYPE_ERR;
NS_IMETHODIMP nsSVGTransform::SetMatrix(nsIDOMSVGMatrix *matrix){  NS_ENSURE_ARG(matrix);    WillModify();  mType = SVG_TRANSFORM_MATRIX;  mAngle = 0.0f;  mOriginX = 0.0f;  mOriginY = 0.0f;    // XXX should we copy the matrix instead of replacing?  mMatrix = matrix;  DidModify();  return NS_OK;}