anchor.diff:      LibraryUpdater,
       Logger;
   
  +import 'package:compiler/implementation/js/js.dart' as jsAst;
  +
   part 'caching_compiler.dart';
   
   const List<String> INCREMENTAL_OPTIONS = const <String>[
  
positive.code:   final List<String> options;
    final CompilerOutputProvider outputProvider;
    final Map<String, dynamic> environment;
  
    Compiler _compiler;
  
  
negative.code:       if (compiler.compilationFailed) {
          return null;
        } else {
          String update = updater.computeUpdateJs();
          _updates.add(update);
          return update;
        }
      });
    }
  
    String allUpdates() {
      jsAst.Node updates = jsAst.js.escapedString(_updates.join(""));
  
      jsAst.FunctionDeclaration mainRunner = jsAst.js.statement(r"""
  function dartMainRunner(main, args) {
    $dart_unsafe_eval.patch(#);
    return main(args);
  }""", updates);
  
  
      jsAst.Printer printer = new jsAst.Printer(_compiler, null);
      printer.blockOutWithoutBraces(mainRunner);
      return printer.outBuffer.getText();
    }
  }
  