anchor.diff:        : super(fileSystem, platformKernel, strongMode: strongMode);
   
     @override
  -  Future<Program> compile(Uri script) async {
  +  Future<Program> compileInternal(Uri script) async {
       return requireMain
           ? kernelForProgram(script, options)
           : kernelForBuildUnit([script], options..chaseDependencies = true);
  
positive.code: ///
  library runtime.tools.kernel_service;
  
  import 'dart:async' show Future;
  import 'dart:io' show Platform hide FileSystemEntity;
  import 'dart:isolate';
  import 'dart:typed_data' show Uint8List;
  
  
negative.code:       };
    }
  
    Future<Program> compile(Uri script) {
      return runWithPrintToStderr(() => compileInternal(script));
    }
  
    Future<Program> compileInternal(Uri script);
  }
  
  class IncrementalCompiler extends Compiler {
  