anchor.diff:  class Dart2jsCompilerConfiguration extends Dart2xCompilerConfiguration {
     final bool isCsp;
     final bool useCps;
  -  final bool isBrowser;
     final List<String> extraDart2jsOptions;
     // We cache the extended environment to save memory.
     static Map<String, String> cpsFlagCache;
  
positive.code:       bool useSdk,
        bool this.useCps,
        bool this.isCsp,
        bool this.isBrowser,
        this.extraDart2jsOptions})
        : super('dart2js',
              isDebug: isDebug,
  
negative.code:             useCps: useCps,
              useSdk: useSdk,
              isCsp: isCsp,
              extraDart2jsOptions:
                  TestUtils.getExtraOptions(configuration, 'dart2js_options'));
        case 'dart2app':
  