fix language_tests.js to use strict mode

test/browser/language_tests.js

 // Copyright (c) 2015, 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.
 
-var _isolate_helper = dart_library.import('dart/_isolate_helper');
-_isolate_helper.startRootIsolate(function() {}, []);
+(function() {
+  'use strict';
 
-function dartLanguageTests(tests) {
-  for (const name of tests) {
-    test(name, () => {
-      dart_library.import('language/' + name).main();
-    })
+  let _isolate_helper = dart_library.import('dart/_isolate_helper');
+  _isolate_helper.startRootIsolate(function() {}, []);
+
+  function dartLanguageTests(tests) {
+    for (const name of tests) {
+      test(name, () => {
+        console.debug('Running language test: ' + name);
+        dart_library.import('language/' + name).main();
+      });
+    }
   }
-}
 
-suite('sync*', () => {
-  "use strict";
+  suite('sync*', () => {
+    test('syncstar_syntax', () => {
+      dart_library.import('syncstar_syntax').main();
+    });
 
-  test('syncstar_syntax', () => {
-    dart_library.import('syncstar_syntax').main();
+    dartLanguageTests([
+      'syncstar_yield_test',
+      'syncstar_yieldstar_test'
+    ]);
   });
 
-  dartLanguageTests([
-    'syncstar_yield_test',
-    'syncstar_yieldstart_test'
-  ]);
-});
+  dart_library.import('language/async_await_test').main();
 
-dart_library.import('language/async_await_test').main();
+  suite('async', () => {
+    dartLanguageTests([
+      'async_and_or_test',
+      'async_await_catch_regression_test',
+      // TODO(jmesserly): fix errors
+      // 'async_backwards_compatibility_1_test',
+      'async_backwards_compatibility_2_test',
+      'async_break_in_finally_test',
+      // TODO(jmesserly): https://github.com/dart-lang/dev_compiler/issues/263
+      // 'async_continue_label_test',
+      'async_control_structures_test',
+      'async_finally_rethrow_test',
+      // TODO(jmesserly): fix errors
+      // 'async_or_generator_return_type_stacktrace_test',
+      'async_regression_23058_test',
+      'async_rethrow_test',
+      // TODO(jmesserly): fix errors
+      // 'async_return_types_test',
+      'async_switch_test',
+      'async_test',
+      'async_this_bound_test',
+      'async_throw_in_catch_test'
+    ]);
+  });
 
-suite('async', () => {
-  dartLanguageTests([
-    'async_and_or_test',
-    'async_await_catch_regression_test',
-    // TODO(jmesserly): fix errors
-    // 'async_backwards_compatibility_1_test',
-    'async_backwards_compatibility_2_test',
-    'async_break_in_finally_test',
-    // TODO(jmesserly): https://github.com/dart-lang/dev_compiler/issues/263
-    // 'async_continue_label_test',
-    'async_control_structures_test',
-    'async_finally_rethrow_test',
-    // TODO(jmesserly): fix errors
-    // 'async_or_generator_return_type_stacktrace_test',
-    'async_regression_23058_test',
-    'async_rethrow_test',
-    // TODO(jmesserly): fix errors
-    // 'async_return_types_test',
-    'async_switch_test',
-    'async_test',
-    'async_this_bound_test',
-    'async_throw_in_catch_test'
-  ]);
-})
+  dart_library.import('language/async_star_test').main();
 
-dart_library.import('language/async_star_test').main();
-
-suite('async*', () => {
-  dartLanguageTests([
-    // TODO(jmesserly): figure out why this test is hanging.
-    //'async_star_cancel_and_throw_in_finally_test',
-    'async_star_regression_23116_test',
-    'asyncstar_concat_test',
-    'asyncstar_throw_in_catch_test',
-    'asyncstar_yield_test',
-    'asyncstar_yieldstar_test'
-  ]);
-});
+  suite('async*', () => {
+    dartLanguageTests([
+      // TODO(jmesserly): figure out why this test is hanging.
+      //'async_star_cancel_and_throw_in_finally_test',
+      'async_star_regression_23116_test',
+      'asyncstar_concat_test',
+      'asyncstar_throw_in_catch_test',
+      'asyncstar_yield_test',
+      'asyncstar_yieldstar_test'
+    ]);
+  });
+})();