Shard tests run by test.dart, so they can be distributed to multiple machines.

tools/testing/dart/test_options.dart

Index: tools/testing/dart/test_options.dart
diff --git a/tools/testing/dart/test_options.dart b/tools/testing/dart/test_options.dart
index 35f5b3e2aaa7da782a645cd29f9f0414f4f1474d..c36c6391c17b2b4e2a881850d3d11a3220d7381a 100644
--- a/tools/testing/dart/test_options.dart
+++ b/tools/testing/dart/test_options.dart
@@ -151,7 +151,21 @@ Controls how dart code is compiled and executed.
               'The number of parallel tasks to run',
               ['-j', '--tasks'],
               [],
-              new Platform().numberOfProcessors(),
+          new Platform().numberOfProcessors(),

[Bill Hesse, 2012/03/23 22:33:56]

Fix this stray indentation.

+          'int'),
+          new _TestOptionSpecification(
+              'shards',
+              'The number of instances that the tests will be sharded over',
+              ['--shards'],
+              [],
+              1,
+              'int'),
+          new _TestOptionSpecification(
+              'shard',
+              'The index of this instance when running in sharded mode',

[Mads Ager (google), 2012/03/23 23:38:20]

Maybe we should add an early bailout check somewhere (just before expanding the
configurations maybe) that the value of the shard option is between 1 and the
shards options.

+              ['--shard'],
+              [],
+              1,
               'int'),
           new _TestOptionSpecification(
               'help',