Add support for --dart2js-path and --dart2js-args.

lib/src/runner/configuration/args.dart

 // Copyright (c) 2016, 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.
 
 import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:boolean_selector/boolean_selector.dart';
 
 import '../../backend/test_platform.dart';
@@ skipping 67 matching lines @@
       valueHelp: 'port');
   parser.addOption("timeout",
       help: 'The default test timeout. For example: 15s, 2x, none',
       defaultsTo: '30s');
   parser.addFlag("pause-after-load",
       help: 'Pauses for debugging before any tests execute.\n'
           'Implies --concurrency=1 and --timeout=none.\n'
           'Currently only supported for browser tests.',
       negatable: false);
 
-  // These are used by the internal Google test runner, so they're hidden from
-  // the --help output but still supported as stable API surface. See
-  // [Configuration.shardIndex] for details on their semantics.
-  parser.addOption("shard-index", hide: true);
-  parser.addOption("total-shards", hide: true);
-
   parser.addSeparator("======== Output");
   parser.addOption("reporter",
       abbr: 'r',
       help: 'The runner used to print test results.',
       defaultsTo: defaultReporter,
       allowed: allReporters,
       allowedHelp: {
     'compact': 'A single line, updated continuously.',
     'expanded': 'A separate line for each update.',
     'json': 'A machine-readable format (see https://goo.gl/0HRhdZ).'
   });
   parser.addFlag("verbose-trace", negatable: false,
       help: 'Whether to emit stack traces with core library frames.');
   parser.addFlag("js-trace", negatable: false,
       help: 'Whether to emit raw JavaScript stack traces for browser tests.');
   parser.addFlag("color",
       help: 'Whether to use terminal colors.\n(auto-detected by default)');
 
+  /// The following options are used only by the internal Google test runner.
+  /// They're hidden and not supported as stable API surface outside Google.
+
+  parser.addOption("dart2js-path",
+      help: 'The path to the dart2js executable.', hide: true);
+  parser.addOption("dart2js-args",
+      help: 'Extra arguments to pass to dart2js.',
+      allowMultiple: true, hide: true);
+  parser.addOption("total-shards",
+      help: 'The total number of invocations of the test runner being run.',
+      hide: true);
+  parser.addOption("shard-index",
+      help: 'The index of this test runner invocation (of --total-shards).',
+      hide: true);
+
   return parser;
 })();
 
 /// The usage string for the command-line arguments.
 String get usage => _parser.usage;
 
 /// Parses the configuration from [args].
 ///
 /// Throws a [FormatException] if [args] are invalid.
 Configuration parse(List<String> args) => new _Parser(args).parse();
@@ skipping 46 matching lines @@
     }
 
     return new Configuration(
         help: _ifParsed('help'),
         version: _ifParsed('version'),
         verboseTrace: _ifParsed('verbose-trace'),
         jsTrace: _ifParsed('js-trace'),
         pauseAfterLoad: _ifParsed('pause-after-load'),
         color: _ifParsed('color'),
         packageRoot: _ifParsed('package-root'),
+        dart2jsPath: _ifParsed('dart2js-path'),
+        dart2jsArgs: _ifParsed('dart2js-args') as List<String>,
         reporter: _ifParsed('reporter'),
         pubServePort: _parseOption('pub-serve', int.parse),
         concurrency: _parseOption('concurrency', int.parse),
         shardIndex: shardIndex,
         totalShards: totalShards,
         timeout: _parseOption('timeout', (value) => new Timeout.parse(value)),
         patterns: patterns,
         platforms: (_ifParsed('platform') as List<String>)
             ?.map(TestPlatform.find),
         chosenPresets: _ifParsed('preset') as List<String>,
@@ skipping 24 matching lines @@
   /// information.
   /*=T*/ _wrapFormatException/*<T>*/(String name, /*=T*/ parse()) {
     try {
       return parse();
     } on FormatException catch (error) {
       throw new FormatException('Couldn\'t parse --$name "${_options[name]}": '
           '${error.message}');
     }
   }
 }