First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/no_duplicate_stub_test.dart

Index: tests/compiler/dart2js/no_duplicate_stub_test.dart
diff --git a/tests/compiler/dart2js/no_duplicate_stub_test.dart b/tests/compiler/dart2js/no_duplicate_stub_test.dart
index 3213529a77f9861e68b7af1dc8656ded6b4498f2..8ace11b9c6fbb6f09306e41a36ad51ea3f0f1723 100644
--- a/tests/compiler/dart2js/no_duplicate_stub_test.dart
+++ b/tests/compiler/dart2js/no_duplicate_stub_test.dart
@@ -2,6 +2,7 @@
 // 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:async_helper/async_helper.dart";
 import 'compiler_helper.dart';
 
 const String TEST = r"""
@@ -28,8 +29,9 @@ baz(a) {
 """;
 
 main() {
-  String generated = compileAll(TEST);
-  RegExp regexp = new RegExp('foo\\\$1\\\$a: function');
-  Iterator<Match> matches = regexp.allMatches(generated).iterator;
-  checkNumberOfMatches(matches, 1);
+  asyncTest(() => compileAll(TEST).then((generated) {
+    RegExp regexp = new RegExp('foo\\\$1\\\$a: function');
+    Iterator<Match> matches = regexp.allMatches(generated).iterator;
+    checkNumberOfMatches(matches, 1);
+  }));
 }