_checkInternalCacheUpToDate(internalCache, drawer) {
            // We respect existing records, unless they are outdated. Invalidation routine by its nature
            // destroys internal cache, therefore we do not need to check if internal cache is consistent with its parent.
            return internalCache && internalCache.loaded && internalCache.tstamp >= drawer._dataNeedsRefresh;
        }
@param {OpenSeadragon.InternalCacheRecord} internalCache
@param {OpenSeadragon.DrawerBase} drawer
@return {boolean} false if the internal cache is outdated
@private