anchor.diff:      FunctionType functionType;
       var parent = body.parent;
       if (parent is Declaration) {
  -      functionType = _elementType(parent.declaredElement) as FunctionType;
  +      functionType = _elementType(parent.declaredElement!) as FunctionType;
       } else {
         assert(parent is FunctionExpression);
         functionType = (parent as FunctionExpression).staticType as FunctionType;
  
positive.code:   void visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
      var field = node.fieldName;
      var element = field.staticElement;
      DartType staticType = _elementType(element);
      checkAssignment(node.expression, staticType);
      node.visitChildren(this);
    }
  
  
negative.code:     var arguments = node.argumentList;
      var element = node.constructorName.staticElement;
      if (element != null) {
        var type = element.type;
        checkArgumentList(arguments, type);
      }
      node.visitChildren(this);
  