anchor.diff:    }
   
     /**
  +   * Create a new entry in the references table ([UnlinkedLibrary.references]
  +   * and [LinkedLibrary.references]) representing an entity having the given
  +   * [name] and [kind].  If [unit] is given, it is the index of the compilation
  +   * unit containing the entity being referred to.  If [prefixReference] is
  +   * given, it indicates the entry in the references table for the prefix.
  +   */
  +  int serializeUnlinkedReference(String name, ReferenceKind kind,
  +      {int unit: 0, int prefixReference: 0}) {
  +    assert(unlinkedReferences.length == linkedReferences.length);
  +    int index = unlinkedReferences.length;
  +    unlinkedReferences.add(new UnlinkedReferenceBuilder(
  +        name: name, prefixReference: prefixReference));
  +    linkedReferences.add(new LinkedReferenceBuilder(kind: kind, unit: unit));
  +    return index;
  +  }
  +
  +  /**
      * Return the index of the entry in the references table
      * ([UnlinkedLibrary.references] and [LinkedLibrary.references]) used for
      * unresolved references.  A new entry is added to the table if necessary to
  
positive.code:     if (name == null) {
        return typeRef;
      } else {
        int typeId = typeRef.reference;
        LinkedReference typeLinkedRef = serializer.linkedReferences[typeId];
        serializer.unlinkedReferences.add(new UnlinkedReferenceBuilder(
            name: name.name, prefixReference: typeId));
        int refId = serializer.linkedReferences.length;
        serializer.linkedReferences.add(new LinkedReferenceBuilder(
            kind: ReferenceKind.constructor, unit: typeLinkedRef.unit));
        return new EntityRefBuilder(
            reference: refId, typeArguments: typeRef.typeArguments);
      }
  
negative.code:         }
        }
        for (ConstructorElement constructor in cls.constructors) {
          if (constructor.isPublic && constructor.name.isNotEmpty) {
            // TODO(paulberry): should numTypeParameters include class params?
            bs.add(new UnlinkedPublicNameBuilder(
                name: constructor.name,
  