anchor.diff:      // these would be invisible as well and are therefore excluded from the
       // tree).
       assert(!node.isInvisible || children.isEmpty);
  -    yield node;
  +    result.add(node);
     }
   
     @override
  
positive.code:           continue;
          if (!config.isCompatibleWith(fragment.config))
            toBeMarkedExplicit.add(fragment);
          for (final _InterestingSemanticsFragment siblingFragment in fragments.sublist(0, fragments.length - 1)) {
            if (!fragment.config!.isCompatibleWith(siblingFragment.config)) {
              toBeMarkedExplicit.add(fragment);
              toBeMarkedExplicit.add(siblingFragment);
  
negative.code: 
      node.rect = owner.semanticBounds;
  
      final List<SemanticsNode> children = <SemanticsNode>[];
      for (final _InterestingSemanticsFragment fragment in _children) {
        assert(fragment.config == null);
        fragment.compileChildren(
          parentSemanticsClipRect: parentSemanticsClipRect,
          parentPaintClipRect: parentPaintClipRect,
          elevationAdjustment: 0.0,
          result: children,
        );
      }
      node.updateWith(config: null, childrenInInversePaintOrder: children);
  
      // The root node is the only semantics node allowed to be invisible. This
  