This is a fixed up version of:

tools/testing/dart/test_suite.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 2207 matching lines @@
     } else if (system == 'macos') {
       result = 'xcodebuild/';
     } else if (system == 'windows') {
       result = 'build/';
     }
     return result;
   }
 
   static List<String> standardOptions(Map configuration) {
     List args = ["--ignore-unrecognized-flags"];
-    if (configuration["checked"]) {
-      args.add('--enable_asserts');
-      args.add("--enable_type_checks");
-    }
     String compiler = configuration["compiler"];
     if (compiler == "dart2js") {
       args = ['--generate-code-with-compile-time-errors', '--test-mode'];
       if (configuration["checked"]) {
         args.add('--enable-checked-mode');
       }
       // args.add("--verbose");
       if (!isBrowserRuntime(configuration['runtime'])) {
         args.add("--allow-mock-compilation");
         args.add("--categories=all");
@@ skipping 182 matching lines @@
       for (var key in PATH_REPLACEMENTS.keys) {
         if (path.startsWith(key)) {
           path = path.replaceFirst(key, PATH_REPLACEMENTS[key]);
           break;
         }
       }
     }
     return path;
   }
 }