Search for a Charged Higgs Boson Decaying into a Heavy Neutral Higgs Boson and a W Boson in Proton-Proton Collisions at S\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \