anchor.diff:  
     /// Internal method.
     Future loadEnsureLoadedComponents(
  -      Set<Uri> reusedLibraryUris, List<LibraryBuilder> reusedLibraries) async {
  +      List<LibraryBuilder> reusedLibraries) async {
       if (modulesToLoad != null) {
         bool loadedAnything = false;
         for (Component module in modulesToLoad) {
           bool usedComponent = false;
           for (Library lib in module.libraries) {
  -          if (!reusedLibraryUris.contains(lib.importUri)) {
  +          if (!dillLoadedData.loader.builders.containsKey(lib.importUri)) {
               dillLoadedData.loader.libraries.add(lib);
               dillLoadedData.addLibrary(lib);
               reusedLibraries.add(dillLoadedData.loader.read(lib.importUri, -1));
  
positive.code:             .addAll(oldDillLoadedData.loader.libraries);
        }
  
        for (LibraryBuilder builder in notReusedLibraries) {
          Library lib = builder.target;
          CompilerContext.current.uriToSource.remove(builder.fileUri);
  
          // Remove component problems for libraries we don't reuse.
          if (remainingComponentProblems.isNotEmpty) {
            removeLibraryFromRemainingComponentProblems(lib, uriTranslator);
          }
        }
  
        if (hierarchy != null) {
          List<Library> removedLibraries = new List<Library>();
          for (LibraryBuilder builder in notReusedLibraries) {
  
negative.code:       List<LibraryBuilder> reusedLibraries = computeReusedLibraries(
            invalidatedUris, uriTranslator,
            notReused: notReusedLibraries);
  
        bool removedDillBuilders = false;
        for (LibraryBuilder builder in notReusedLibraries) {
          CompilerContext.current.uriToSource.remove(builder.fileUri);
  
          LibraryBuilder dillBuilder =
              dillLoadedData.loader.builders.remove(builder.uri);
          if (dillBuilder != null) {
            removedDillBuilders = true;
            userBuilders?.remove(builder.uri);
          }
  
          // Remove component problems for libraries we don't reuse.
          if (remainingComponentProblems.isNotEmpty) {
            Library lib = builder.target;
            removeLibraryFromRemainingComponentProblems(lib, uriTranslator);
          }
        }
  
        if (removedDillBuilders) {
          dillLoadedData.loader.libraries.clear();
          for (LibraryBuilder builder in dillLoadedData.loader.builders.values) {
            dillLoadedData.loader.libraries.add(builder.target);
  