Remove system-provided temporary directory usage from test scripts.

tools/testing/dart/test_options.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.
 
 #library("test_options_parser");
 
 #import("dart:io");
 #import("dart:builtin");
 #import("drt_updater.dart");
 
@@ skipping 174 matching lines @@
               false,
               'bool'),
           new _TestOptionSpecification(
               'list',
               'List tests only, do not run them',
               ['--list'],
               [],
               false,
               'bool'),
           new _TestOptionSpecification(
-              'keep-generated-tests',
-              'Keep the generated files in the temporary directory',
-              ['--keep-generated-tests'],
-              [],
-              false,
-              'bool'),
-          new _TestOptionSpecification(
               'valgrind',
               'Run tests through valgrind',
               ['--valgrind'],
               [],
               false,
               'bool'),
           new _TestOptionSpecification(
               'special-command',
               specialCommandHelp,
               ['--special-command'],
@@ skipping 428 matching lines @@
         return option;
       }
     }
     print('Unknown test option $name');
     exit(1);
   }
 
 
   List<_TestOptionSpecification> _options;
 }