anchor.diff:  ///        [SimpleIdentifier] ':'
   class LabelImpl extends AstNodeImpl implements Label {
     /// The label being associated with the statement.
  -  late SimpleIdentifierImpl _label;
  +  SimpleIdentifierImpl _label;
   
     /// The colon that separates the label from the statement.
     @override
     Token colon;
   
     /// Initialize a newly created label.
  -  LabelImpl(SimpleIdentifierImpl label, this.colon) {
  -    _label = _becomeParentOf(label);
  +  LabelImpl(this._label, this.colon) {
  +    _becomeParentOf(_label);
     }
   
     @override
  
positive.code: class FunctionDeclarationStatementImpl extends StatementImpl
      implements FunctionDeclarationStatement {
    /// The function declaration being wrapped.
    late FunctionDeclarationImpl _functionDeclaration;
  
    /// Initialize a newly created function declaration statement.
    FunctionDeclarationStatementImpl(
        FunctionDeclarationImpl functionDeclaration) {
      _functionDeclaration = _becomeParentOf(functionDeclaration);
    }
  
    @override
  
negative.code:   /// Initialize a newly created do loop.
    DoStatementImpl(
        this.doKeyword,
        this._body,
        this.whileKeyword,
        this.leftParenthesis,
        this._condition,
        this.rightParenthesis,
        this.semicolon) {
      _becomeParentOf(_body);
      _becomeParentOf(_condition);
    }
  
    @override
  