anchor.diff:  }
   
   void usage(ArgParser parser) {
  -  print("Usage: dart run_tests.dart [--build] [--configs=...] "
  +  print("Usage: dart run_tests.dart [--build] [-2] [-1] [--configs=...]"
         "<first file> [last file]");
     print("\n");
     print("Example:");
  
positive.code:   "analyzer-checked-strong": [analyzer, noRuntime, checked, strong, useSdk],
    "analyzer-strong": [analyzer, noRuntime, strong, useSdk],
    "dart2js": [dart2js, chrome, useSdk, dart2jsBatch],
    "dart2js-d8-checked": [dart2js, d8, checked, fastStartup, useSdk, dart2jsBatch],
    "dart2js-jsshell": [dart2js, jsshell, fastStartup, useSdk, dart2jsBatch],
    // TODO(rnystrom): Is it worth running dart2js on Firefox too?
    "dartdevc": [dartdevc, chrome, useSdk, strong],
  };
  
  final buildSteps = [
    // The SDK, which also builds the VM.
  
negative.code:   argParser.addOption("config",
        abbr: "c", allowMultiple: true, help: "Which configurations to run.");
    argParser.addFlag("help");
    argParser.addFlag("1",
        abbr: "1", help: "Run some of the 1.0-supporting configurations.");
    argParser.addFlag("2",
        abbr: "2", help: "Run the 2.0-supporting configurations.");
  
    var argResults = argParser.parse(arguments);
    if (argResults["help"] as bool) {
  