DBC: Adds simdbc64 target, adds arm64 arithmetic overflow logic

tools/testing/dart/test_options.dart

 // Copyright (c) 2013, 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 "drt_updater.dart";
 import "test_suite.dart";
 import "path.dart";
@@ skipping 131 matching lines @@
             'arm',
             'armv6',
             'armv5te',
             'arm64',
             'mips',
             'simarm',
             'simarmv6',
             'simarmv5te',
             'simarm64',
             'simmips',
-            'simdbc'
+            'simdbc',
+            'simdbc64',
           ],
           'x64'),
       new _TestOptionSpecification(
           'system',
           'The operating system to run tests on',
           ['-s', '--system'],
           ['linux', 'macos', 'windows'],
           Platform.operatingSystem),
       new _TestOptionSpecification(
           'checked', 'Run tests in checked mode', ['--checked'], [], false,
@@ skipping 727 matching lines @@
       if (option.keys.contains(name)) {
         return option;
       }
     }
     print('Unknown test option $name');
     exit(1);
   }
 
   List<_TestOptionSpecification> _options;
 }