anchor.diff:        final S typedResult = untypedResult;
         return typedResult;
       }
  -    return super.find<S>(regionOffset);
  -  }
  -
  -  @override
  -  Iterable<S> findAll<S>(Offset regionOffset) sync* {
  -    yield* super.findAll<S>(regionOffset);
  +    return null;
  +  }
  +
  +  @override
  +  Iterable<S> findAll<S>(Offset regionOffset) {
  +    final Iterable<S> childResults = super.findAll<S>(regionOffset);
       if (size != null && !(offset & size).contains(regionOffset)) {
  -      return;
  +      return childResults;
       }
       if (T == S) {
         final Object untypedResult = value;
         final S typedResult = untypedResult;
  -      yield typedResult;
  -    }
  +      return childResults.followedBy(<S>[typedResult]);
  +    }
  +    return childResults;
     }
   
     @override
  
positive.code:                               'for more details.'),
        library: 'rendering library',
        context: ErrorDescription('during compositing'),
        informationCollector: () sync* {
          yield child.toDiagnosticsNode(name: 'Attempted to composite layer', style: DiagnosticsTreeStyle.errorProperty);
          yield predecessor.toDiagnosticsNode(name: 'after layer', style: DiagnosticsTreeStyle.errorProperty);
          yield ErrorDescription('which occupies the same area at a higher elevation.');
        }
      ));
      return <PictureLayer>[
  
negative.code:   }
  
    @override
    Iterable<S> findAll<S>(Offset regionOffset) {
      final Offset transformedOffset = _transformOffset(regionOffset);
      if (transformedOffset == null) {
        return Iterable<S>.empty();
      }
      return super.findAll<S>(transformedOffset);
    }
  
    @override
  