Fix issues when pass null or undefined to add/removeSelection and select method of viewer widget
Fix issues when pass null or undefined to add/removeSelection and select method of viewer widget

partridgejiang/Kekule.js,partridgejiang/Kekule.js,partridgejiang/Kekule.js,partridgejiang/Kekule.js,partridgejiang/Kekule.js,partridgejiang/Kekule.js