anchor.diff:      ArgResults options, {
       IncrementalKernelGenerator generator,
     }) async {
  -    _filename = filename;
  +    final Uri filenameUri = Uri.base.resolveUri(new Uri.file(filename));
       _kernelBinaryFilename = "$filename.dill";
       final String boundaryKey = new Uuid().generateV4();
       _outputStream.writeln("result $boundaryKey");
  
positive.code:   }
  
    Uri _ensureFolderPath(String path) {
      // This is a URI, not a file path, so the forward slash is correct even
      // on Windows.
      if (!path.endsWith('/')) {
        path = '$path/';
      }
      return Uri.base.resolve(path);
    }
  
    /// Runs the given function [f] in a Zone that redirects all prints into
  
negative.code:       _generator = generator != null
            ? generator
            : await IncrementalKernelGenerator.newInstance(
                compilerOptions, filenameUri,
                useMinimalGenerator: true);
        final DeltaProgram deltaProgram =
            await _runWithPrintRedirection(() => _generator.computeDelta());
  