Add support to dart2js for option --enable-asserts.

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 200 matching lines @@
           false,
           type: 'bool'),
       new _TestOptionSpecification(
           'fast_startup',
           'Pass the --fast-startup flag to dart2js',
           ['--fast-startup'],
           [],
           false,
           type: 'bool'),
       new _TestOptionSpecification(
+          'enable_asserts',
+          'Pass the --enable-asserts flag to dart2js',

[sra1, 2017/05/19 16:51:35]

This should be made to work for VM tests too.

[eernst, 2017/05/23 17:09:55]

Done.

+          ['--enable-asserts'],
+          [],
+          false,
+          type: 'bool'),
+      new _TestOptionSpecification(
           'dart2js_with_kernel',
           'Enable the internal pipeline in dart2js to use kernel',
           ['--dart2js-with-kernel'],
           [],
           false,
           type: 'bool'),
       new _TestOptionSpecification('hot_reload', 'Run hot reload stress tests',
           ['--hot-reload'], [], false,
           type: 'bool'),
       new _TestOptionSpecification(
@@ skipping 547 matching lines @@
     if (configuration['verbose'] && configuration['progress'] != 'buildbot') {
       configuration['progress'] = 'verbose';
     }
 
     // Create the artificial negative options that test status files
     // expect.
     configuration['unchecked'] = !configuration['checked'];
     configuration['host_unchecked'] = !configuration['host_checked'];
     configuration['unminified'] = !configuration['minified'];
     configuration['nocsp'] = !configuration['csp'];
+    configuration['no_enable_asserts'] = !configuration['enable_asserts'];
 
     String runtime = configuration['runtime'];
     if (runtime == 'firefox') {
       configuration['runtime'] == 'ff';
     }
 
     String compiler = configuration['compiler'];
     configuration['browser'] = TestUtils.isBrowserRuntime(runtime);
     configuration['analyzer'] = TestUtils.isCommandLineAnalyzer(compiler);
 
@@ skipping 205 matching lines @@
         return option;
       }
     }
     print('Unknown test option $name');
     exit(1);
     return null; // Unreachable.
   }
 
   List<_TestOptionSpecification> _options;
 }