anchor.diff:  
     void processNativeClasses(Enqueuer world,
                               Collection<LibraryElement> libraries) {
  -  }
  -
  -  /**
  -   * Adds given class element with its member element to resolved classes
  -   * collections.
  -   */
  -  void addMemberToClass(Element element, ClassElement classElement) {
  -    // ${element} should have ${classElement} as enclosing.
  -    assert(element.isMember());
  -    Set<Element> resolvedElementsInClass = resolvedClassMembers.putIfAbsent(
  -        classElement, () => new Set<Element>());
  -    resolvedElementsInClass.add(element);
     }
   
     void assembleProgram() {
  
positive.code: 
    Map<Element, TreeElements> get resolvedElements() =>
        compiler.enqueuer.resolution.resolvedElements;
    Map<ClassElement, Set<Element>> resolvedClassMembers;
  
    DartBackend(Compiler compiler, [bool validateUnparse = false])
        : tasks = <CompilerTask>[],
        unparseValidator = new UnparseValidator(compiler, validateUnparse),
        resolvedClassMembers = new Map<ClassElement, Set<Element>>(),
        super(compiler) {
      tasks.add(unparseValidator);
    }
  
negative.code:     Set<TypedefElement> typedefs = new Set<TypedefElement>();
      Set<ClassElement> classes = new Set<ClassElement>();
      Set<Element> elements = new Set<Element>();
      Map<ClassElement, Set<Element>> resolvedClassMembers =
          new Map<ClassElement, Set<Element>>();
      PlaceholderCollector collector = new PlaceholderCollector(compiler);
      resolvedElements.forEach((element, treeElements) {
        if (!shouldOutput(element)) return;
  