anchor.diff:    PlaceholderCollector(this.compiler, this.fixedMemberNames, this.elementAsts) :
         nullNodes = new Set<Node>(),
         unresolvedNodes = new Set<Identifier>(),
  -      elementNodes = new Map<Element, Set<Node>>(),
  +      elementNodes = new Map<Element, Set<Identifier>>(),
         functionScopes = new Map<FunctionElement, FunctionScope>(),
         privateNodes = new Map<LibraryElement, Set<Identifier>>(),
         declarationTypePlaceholders = new List<DeclarationTypePlaceholder>(),
  
positive.code:           'Should never make element placeholder for dynamic type element',
            node);
      }
      elementNodes.putIfAbsent(element, () => new Set<Node>()).add(node);
    }
  
    void makePrivateIdentifier(Identifier node) {
  
negative.code:   final Map<Element, ElementAst> elementAsts;
    final Set<Node> nullNodes;  // Nodes that should not be in output.
    final Set<Identifier> unresolvedNodes;
    final Map<Element, Set<Identifier>> elementNodes;
    final Map<FunctionElement, FunctionScope> functionScopes;
    final Map<LibraryElement, Set<Identifier>> privateNodes;
    final List<DeclarationTypePlaceholder> declarationTypePlaceholders;
  