anchor.diff:  
   // TODO: Implement memory based limiting, once `approximateByteCount` is exposed in engine
   class PictureCache {
  -  final Map<Object, PictureStreamCompleter> _cache = <Object, PictureStreamCompleter>{};
  +  final Map<Object, PictureStreamCompleter> _cache =
  +      <Object, PictureStreamCompleter>{};
   
     /// Maximum number of entries to store in the cache.
     ///
  
positive.code:     assert(_cache.length <= maximumSize);
      return result;
    }
  }
negative.code:   /// evicted when adding a new entry.
    int get maximumSize => _maximumSize;
    int _maximumSize = _kDefaultSize;
  
    /// Changes the maximum cache size.
    ///
    /// If the new size is smaller than the current number of elements, the
  