First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/inferrer_factory_test.dart

Index: tests/compiler/dart2js/inferrer_factory_test.dart
diff --git a/tests/compiler/dart2js/inferrer_factory_test.dart b/tests/compiler/dart2js/inferrer_factory_test.dart
index 7e2c9ec0fa5add3f45fb1e730512197630f35c65..a8b225c6e8fb65877bb3509a7eec319bdcd0d5b1 100644
--- a/tests/compiler/dart2js/inferrer_factory_test.dart
+++ b/tests/compiler/dart2js/inferrer_factory_test.dart
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
 import 'compiler_helper.dart';
 
 const String TEST1 = r"""
@@ -22,9 +23,10 @@ main() {
 """;
 
 main() {
-  String generated = compileAll(TEST1);
-  // Check that we're using the index operator on the object returned
-  // by the A factory.
-  Expect.isTrue(generated.contains('[0] = 42'));
+  asyncTest(() => compileAll(TEST1).then((generated) {
+    // Check that we're using the index operator on the object returned
+    // by the A factory.
+    Expect.isTrue(generated.contains('[0] = 42'));
+  }));
 }