anchor.diff:    }
   
     @override
  -  PackageBundle getLinkedBundle() => null;
  +  PackageBundle getLinkedBundle() {
  +    if (_bundle == null) {
  +      List<Source> librarySources = sdkLibraries
  +          .map((SdkLibrary library) => mapDartUri(library.shortName))
  +          .toList();
  +      List<int> bytes = new SummaryBuilder(
  +              librarySources, context, context.analysisOptions.strongMode)
  +          .build();
  +      _bundle = new PackageBundle.fromBuffer(bytes);
  +    }
  +    return _bundle;
  +  }
   
     @override
     SdkLibrary getSdkLibrary(String dartUri) {
  
positive.code: import 'package:analyzer/src/generated/sdk.dart';
  import 'package:analyzer/src/generated/source.dart';
  import 'package:analyzer/src/summary/idl.dart' show PackageBundle;
  
  class MockSdk implements DartSdk {
    static const MockSdkLibrary LIB_CORE = const MockSdkLibrary(
  
negative.code:    * The [AnalysisContext] which is used for all of the sources.
     */
    InternalAnalysisContext _analysisContext;
  
    /**
     * The cached linked bundle of the SDK.
     */
    PackageBundle _bundle;
  
    MockSdk({resource.ResourceProvider resourceProvider})
        : provider = resourceProvider ?? new resource.MemoryResourceProvider() {
  