function features()
            {
                return { offsetWidth: this.offsetWidth, offsetHeight: this.offsetHeight, naturalWidth: this.naturalWidth, naturalHeight: this.naturalHeight, currentSrc: this.currentSrc };
            }
@return {!{offsetWidth: number, offsetHeight: number, naturalWidth: number, naturalHeight: number, currentSrc: (string|undefined)}}
@suppressReceiverCheck
@this {!Element}