anchor.diff:        if (body != null) {
           _overrideManager.enterScope();
           try {
  -          _propagateTrueState(condition);
             visitStatementInScope(body);
           } finally {
             _overrideManager.exitScope();
  
positive.code:     node.condition?.accept(this);
      _overrideManager.enterScope();
      try {
        _propagateTrueState(node.condition);
        visitStatementInScope(node.body);
        node.updaters.accept(this);
      } finally {
  
negative.code:     }
      node.accept(elementResolver);
      node.accept(typeAnalyzer);
    }
  
    @override
  