anchor.diff:    /// and iOS's VoiceOver provides an additional hint when the focused object is
     /// a button.
     static const SemanticsFlag isButton = SemanticsFlag._(_kIsButtonIndex);
  +
  +  /// Whether the semantic node represents a link.
  +  ///
  +  /// Platforms have special handling for links, for example, iOS's VoiceOver
  +  /// provides an additional hint when the focused object is a link.
  +  static const SemanticsFlag isLink = SemanticsFlag._(_kIsButtonIndex);
   
     /// Whether the semantic node represents a text field.
     ///
  
positive.code:         return 'SemanticsFlag.isSelected';
        case _kIsButtonIndex:
          return 'SemanticsFlag.isButton';
        case _kIsTextFieldIndex:
          return 'SemanticsFlag.isTextField';
        case _kIsFocusableIndex:
  
negative.code:     _kIsCheckedIndex: isChecked,
      _kIsSelectedIndex: isSelected,
      _kIsButtonIndex: isButton,
      _kIsLinkIndex: isLink,
      _kIsTextFieldIndex: isTextField,
      _kIsFocusableIndex: isFocusable,
      _kIsFocusedIndex: isFocused,
  