Move test.dart into testing/dart.

tools/testing/dart/main.dart

+// Copyright (c) 2017, 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.
+
+/// This file is the entrypoint of the Dart repository's custom test system.
+/// It is used to test:
+///
+///     1. The Dart VM
+///     2. The dart2js compiler
+///     3. The static analyzer
+///     4. The Dart core library
+///     5. Other standard dart libraries (DOM bindings, UI libraries,
+///        IO libraries etc.)
+///
+/// This script is normally invoked by test.py. (test.py finds the Dart VM and
+/// passes along all command line arguments to this script.)
+///
+/// The command line args of this script are documented in "test_options.dart".
+/// They are printed when this script is run with "--help".
+///
+/// The default test directory layout is documented in "test_suite.dart", above
+/// `factory StandardTestSuite.forDirectory`.
+import "dart:io";
+
+import "test_configurations.dart";
+import "test_options.dart";
+import "test_progress.dart";
+import "test_suite.dart";
+
+/// Runs all of the tests specified by the given command line [arguments].
+void main(List<String> arguments) {
+  // This script is in "<repo>/tools/testing/dart".
+  TestUtils.setDartDirUri(Platform.script.resolve('../../..'));
+
+  // Clean up any stale temp directories from previous runs.
+  if (Platform.environment['DART_TESTING_DELETE_TEMPORARY_DIRECTORIES'] ==
+      '1') {
+    LeftOverTempDirPrinter.deleteAll();

[Bill Hesse, 2017/05/02 14:33:08]

I see that this has become a sync call, so OK.

[Bob Nystrom, 2017/05/02 23:48:15]

Yup. I didn't see much benefit to making it async. (Anecdotally, my experience
has been that sync dart:io is often faster than async.) Either way, this isn't
exactly performance critical in the very common case where there are no temp
directories.

+  }
+
+  // Parse the command line arguments to a configuration.
+  var optionsParser = new TestOptionsParser();
+  var configurations = optionsParser.parse(arguments);
+  if (configurations == null || configurations.isEmpty) return;
+
+  // Run all of the configured tests.
+  // TODO(26372): Ensure that all tasks complete and return a future from this
+  // function.
+  testConfigurations(configurations);
+}