removed an unused field.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@11277 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/ResponseHeaderFilter.java

@@ -59,12 +59,10 @@ import java.net.URLEncoder;
  * @author Mike Wille
  */
 public class ResponseHeaderFilter implements Filter {
-	private ServletContext servletContext;
 	private FilterConfig config;
 
 	public void init(FilterConfig filterConfig) throws ServletException {
 		config = filterConfig;
-		servletContext = config.getServletContext();
 	}
 
 	public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException,