anchor.diff:     * or `null` if the normal lookup mechanism should be used.
      */
     String defaultPackagesDirectoryPath;
  +
  +  /**
  +   * The file path of the file containing the summary of the SDK that should be
  +   * used to "analyze" the SDK. This option should only be specified by
  +   * command-line tools such as 'dartanalyzer' or 'ddc'.
  +   */
  +  String dartSdkSummaryPath;
   
     /**
      * The file path of the analysis options file that should be used in place of
  
positive.code:    */
    DartSdk findSdk(
        Map<String, List<Folder>> packageMap, AnalysisOptions options) {
      if (packageMap != null) {
        SdkExtensionFinder extFinder = new SdkExtensionFinder(packageMap);
        List<String> extFilePaths = extFinder.extensionFilePaths;
        EmbedderYamlLocator locator = new EmbedderYamlLocator(packageMap);
  
negative.code: import 'package:analyzer/src/generated/source.dart';
  import 'package:analyzer/src/summary/package_bundle_reader.dart';
  import 'package:analyzer/src/summary/pub_summary.dart';
  import 'package:analyzer/src/summary/summary_sdk.dart';
  import 'package:analyzer/src/task/options.dart';
  import 'package:package_config/packages.dart';
  import 'package:package_config/packages_file.dart';
  