anchor.diff:  
   /// A declaration of a special [Class] and how to find it.
   class _SpecialClassDefinition {
  +  /// The package name in which these special [ModelElement]s can be found.
  +  static const String packageName = 'Dart';
  +
     /// Which specialElement this is.
     final SpecialClass specialClass;
   
  
positive.code: 
    const _SpecialClassDefinition(
        this.specialClass, this.name, this.libraryName, this.specialFileUri,
        {this.required = true, this.packageName = 'Dart'});
  
    /// Get the filename for the Dart Library where this [ModelElement]
    /// is declared, or `null` if its URI does not denote a library in
  
negative.code:   /// can be found.
    final String libraryName;
  
    /// The URI for the library in which this [ModelElement] is defined.
    final String specialFileUri;
  
  