Fix removeEmptyPort

remove hasPort and simplify logic

Author: dxasu

src/net/http/http.go

@@ -113,8 +113,8 @@ func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastInd
 // removeEmptyPort strips the empty port in ":port" to ""
 // as mandated by RFC 3986 Section 6.2.3.
 func removeEmptyPort(host string) string {
-	if hasPort(host) {
-		return strings.TrimSuffix(host, ":")
+	if len(host) > 0 && host[len(host)-1] == ':' {
+		return host[:len(host)-1]
 	}
 	return host
 }