Make dart2js unittests async.

tests/compiler/dart2js/find_my_name_test.dart

 // Copyright (c) 2012, 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 "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart";
 import "mock_compiler.dart";
 import "parser_helper.dart";
 
 String TEST_0 = '''
 class Foo {
   Foo();
   Foo.named();
   factory Foo._internal() => null;
   operator+(other) => null;
 }
 ''';
 
 String TEST_1 = '''
 class Bar {
   const Bar();
   const Bar.named();
   Map<int, List<int>> baz() => null;
 }
 ''';
 
 main() {
-  MockCompiler compiler = new MockCompiler();
-  testClass(TEST_0, compiler);
-  testClass(TEST_1, compiler);
+  asyncTest(() => MockCompiler.create((MockCompiler compiler) {
+    testClass(TEST_0, compiler);
+    testClass(TEST_1, compiler);
+  }));
 }
 
 testClass(String code, MockCompiler compiler) {
   int skip = code.indexOf('{');
   ClassElement cls = parseUnit(code, compiler, compiler.mainApp).head;
   cls.parseNode(compiler);
   cls.forEachLocalMember((Element e) {
     String name = e.name;
     if (e.isConstructor) {
       name = Elements.reconstructConstructorName(e).replaceFirst(r'$', '.');
     }
     Expect.equals(code.indexOf(name, skip), e.position.charOffset);
   });
 }