anchor.diff:  const precompiled = "--runtime=dart_precompiled";
   const noRuntime = "--runtime=none";
   const vm = "--runtime=vm";
  +const d8 = "--runtime=d8";
   const jsshell = "--runtime=jsshell";
   
   const checked = "--checked";
  
positive.code: 
    var tests = scanTests();
  
    var startIndex = findFork(tests, argResults.rest[0]);
    var endIndex = findFork(tests, argResults.rest[1]);
  
    if (startIndex == null || endIndex == null) exit(1);
  
  
negative.code:     return;
    }
  
    var remainingArgs = []..addAll(argResults.rest);
  
    if (remainingArgs.length == 1) {
      remainingArgs.add(remainingArgs.first);
    }
  
    if (remainingArgs.length != 2) {
      usage(argParser);
      exit(1);
    }
  