"[R]oe and Casey say nothing at all about cases in which a physician considers one prohibited method of abortion to be preferable to permissible methods. Today’s majority and Justice O’Connor twist Roe and Casey to apply to the situation in which a woman desires–for whatever reason–an abortion and wishes to obtain the abortion by some particular method. See ante, at 11—12 (majority opinion); ante, at 1—2 (concurring opinion). In other words, the majority and Justice O’Connor fail to distinguish between cases in which health concerns require a woman to obtain an abortion and cases in which health concerns cause a woman who desires an abortion (for whatever reason) to prefer one method over another."