anchor.diff:          return;
         }
         if (options.cfeOnly) return;
  -      _mainLibraryUri = result.rootLibraryUri;
   
         frontendStrategy.registerLoadedLibraries(result);
         for (Uri uri in result.libraries) {
  
positive.code:     if (element == null) return assumeInUserCode;
      Uri libraryUri = _uriFromElement(element);
      if (libraryUri == null) return false;
      Iterable<CodeLocation> userCodeLocations =
          computeUserCodeLocations(assumeInUserCode: assumeInUserCode);
      return userCodeLocations.any(
          (CodeLocation codeLocation) => codeLocation.inSameLocation(libraryUri));
    }
  
    Iterable<CodeLocation> computeUserCodeLocations(
        {bool assumeInUserCode: false}) {
      List<CodeLocation> userCodeLocations = <CodeLocation>[];
      if (_mainLibraryUri != null) {
        userCodeLocations.add(new CodeLocation(_mainLibraryUri));
      }
      if (userCodeLocations.isEmpty && assumeInUserCode) {
        // Assume in user code since [mainApp] has not been set yet.
        userCodeLocations.add(const AnyLocation());
      }
      return userCodeLocations;
    }
  
    /// Return a canonical URI for the source of [element].
  
negative.code:   }
  
    void compileFromKernel(Uri rootLibraryUri, Iterable<Uri> libraries) {
      _userCodeLocations.add(new CodeLocation(rootLibraryUri));
      selfTask.measureSubtask("compileFromKernel", () {
        JClosedWorld closedWorld = selfTask.measureSubtask("computeClosedWorld",
            () => computeClosedWorld(rootLibraryUri, libraries));
  