anchor.diff:  class Test {
     final String code;
     final List<StackTraceLine> expectedLines;
  -
  -  Test(this.code, this.expectedLines);
  +  final List<StackTraceLine> unexpectedLines;
  +
  +  Test(this.code, this.expectedLines, this.unexpectedLines);
   }
   
   const int _LF = 0x0A;
  
positive.code: @NoInline()
  test2() {
    @{2:test2}throw '$EXCEPTION_MARKER';
  }
  ''',
  ];
  
negative.code:   SingleMapping sourceMap = new SingleMapping.fromJson(
        JSON.decode(new File('$output.map').readAsStringSync()));
  
    if (printJs) {
      print('JavaScript output:');
      print(new File(output).readAsStringSync());
    }
    print("Running d8 $output");
    ProcessResult runResult = Process.runSync(d8executable,
        ['sdk/lib/_internal/js_runtime/lib/preambles/d8.js', output]);
  