anchor.diff:    void makePrivateIdentifier(Identifier node) {
       assert(node !== null);
       privateNodes.putIfAbsent(
  -        currentElement.getLibrary(), () => new Set<Node>()).add(node);
  +        currentElement.getLibrary(), () => new Set<Identifier>()).add(node);
     }
   
     void makeUnresolvedPlaceholder(Node node) {
  
positive.code:   final Set<Identifier> unresolvedNodes;
    final Map<Element, Set<Node>> elementNodes;
    final Map<FunctionElement, Set<LocalPlaceholder>> localPlaceholders;
    final Map<LibraryElement, Set<Node>> privateNodes;
    Map<String, LocalPlaceholder> currentLocalPlaceholders;
    Element currentElement;
    TreeElements treeElements;
  
negative.code:       unresolvedNodes = new Set<Identifier>(),
        elementNodes = new Map<Element, Set<Node>>(),
        localPlaceholders = new Map<FunctionElement, Set<LocalPlaceholder>>(),
        privateNodes = new Map<LibraryElement, Set<Identifier>>();
  
    void collectFunctionDeclarationPlaceholders(
        FunctionElement element, FunctionExpression node) {
  