Simplify opened getter
Simplify opened getter

We can skip this.ul since it's always exist.
And element.hasAttribute works great for boolean attrs.

eggpi/awesomplete,vlazar/awesomplete,bchcheng/awesomplete,vlazar/awesomplete,bchcheng/awesomplete,bsvobodny/awesomplete,LeaVerou/awesomplete,LeaVerou/awesomplete,bsvobodny/awesomplete,eggpi/awesomplete