anchor.diff:        directive.element = _libraryElement;
       }
   
  -    {
  -      // TODO(scheglov) fill these maps?
  -      DirectiveResolver resolver = new DirectiveResolver({}, {}, {});
  -      definingCompilationUnit.accept(resolver);
  -    }
  +    // TODO(scheglov) remove DirectiveResolver class
     }
   
     void _resolveFile(FileState file, CompilationUnit unit) {
  
positive.code:       if (directive is LibraryDirective) {
          libraryNameNode = directive.name;
          directivesToResolve.add(directive);
        } else if (directive is PartDirective) {
          hasPartDirective = true;
          StringLiteral partUri = directive.uri;
  
negative.code:   }
  
    /**
     * Return `true` if the given [source] is a library.
     */
    bool _isLibrarySource(Source source) {
      String uriStr = source.uri.toString();
      return _store.unlinkedMap[uriStr]?.isPartOf == false;
    }
  
    /**
     * Return a new parsed unresolved [CompilationUnit].
     */
    CompilationUnit _parse(FileState file) {
  