anchor.diff:      // be invalidated by the normal approach anyway.
       if (_generator.initialized) return null;
   
  -    final File f = new File(_initializeFromDill);
  +    final File f = File(_initializeFromDill);
       if (!f.existsSync()) return null;
   
       Component component;
  
positive.code: 
      for (String package in newPackages.keys) {
        List<Library> libraries = newPackages[package];
        Component singleLibrary = new Component(
            libraries: libraries,
            uriToSource: deltaProgram.uriToSource,
            nameRoot: deltaProgram.root);
        ByteSink byteSink = new ByteSink();
        final BinaryPrinter printer = printerFactory.newBinaryPrinter(byteSink);
        printer.writeComponentFile(singleLibrary);
  
        // Record things this package blob dependent on.
        Set<Uri> libraryUris = new Set<Uri>();
        for (Library lib in libraries) {
          libraryUris.add(lib.fileUri);
        }
        Set<Uri> deps = new Set<Uri>();
        for (Library lib in libraries) {
          for (LibraryDependency dep in lib.dependencies) {
            Library dependencyLibrary = dep.importedLibraryReference.asLibrary;
  
negative.code:       setVMEnvironmentDefines(environmentDefines, _compilerOptions);
  
        _compilerOptions.omitPlatform = false;
        _generator = generator ?? _createGenerator(Uri.file(_initializeFromDill));
        await invalidateIfInitializingFromDill();
        Component component =
            await _runWithPrintRedirection(() => _generator.compile());
        results = KernelCompilationResults(
            component,
            _generator.getClassHierarchy(),
            _generator.getCoreTypes(),
  