anchor.diff:  class MapLiteralEntryImpl extends CollectionElementImpl
       implements MapLiteralEntry {
     /// The expression computing the key with which the value will be associated.
  -  late ExpressionImpl _key;
  +  ExpressionImpl _key;
   
     /// The colon that separates the key from the value.
     @override
     Token separator;
   
     /// The expression computing the value that will be associated with the key.
  -  late ExpressionImpl _value;
  +  ExpressionImpl _value;
   
     /// Initialize a newly created map literal entry.
  -  MapLiteralEntryImpl(
  -      ExpressionImpl key, this.separator, ExpressionImpl value) {
  -    _key = _becomeParentOf(key);
  -    _value = _becomeParentOf(value);
  +  MapLiteralEntryImpl(this._key, this.separator, this._value) {
  +    _becomeParentOf(_key);
  +    _becomeParentOf(_value);
     }
   
     @override
  
positive.code:   MethodElement? staticElement;
  
    /// Initialize a newly created prefix expression.
    PrefixExpressionImpl(this.operator, ExpressionImpl operand) {
      _operand = _becomeParentOf(operand);
    }
  
    @override
  
negative.code: ///        [SimpleIdentifier]* 'case' [Expression] ':' [Statement]*
  class SwitchCaseImpl extends SwitchMemberImpl implements SwitchCase {
    /// The expression controlling whether the statements will be executed.
    ExpressionImpl _expression;
  
    /// Initialize a newly created switch case. The list of [labels] can be `null`
    /// if there are no labels.
    SwitchCaseImpl(List<Label> labels, Token keyword, this._expression,
        Token colon, List<Statement> statements)
        : super(labels, keyword, colon, statements) {
      _becomeParentOf(_expression);
    }
  
    @override
  