clearDrawerInternalCache(drawer) {
            const drawerId = drawer.getId();
            for (let zombie of this._zombiesLoaded) {
                if (zombie) {
                    zombie.destroyInternalCache(drawerId);
                }
            }
            for (let cache of this._cachesLoaded) {
                if (cache) {
                    cache.destroyInternalCache(drawerId);
                }
            }
        }
Clean up internal drawer data for a given drawer
@param {OpenSeadragon.DrawerBase} drawer