First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/field_codegen_test.dart

Index: tests/compiler/dart2js/field_codegen_test.dart
diff --git a/tests/compiler/dart2js/field_codegen_test.dart b/tests/compiler/dart2js/field_codegen_test.dart
index d9a8aec6543750968bd980ce3c29bcb063f4c160..eb1a6c4c3d726c14728ff9cbf34d645d354d29ef 100644
--- a/tests/compiler/dart2js/field_codegen_test.dart
+++ b/tests/compiler/dart2js/field_codegen_test.dart
@@ -4,6 +4,7 @@
 // Test that parameters keep their names in the output.
 
 import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
 import 'compiler_helper.dart';
 import 'parser_helper.dart';
 
@@ -20,8 +21,11 @@ main() { return x; }
 """;
 
 main() {
-  String generated = compileAll(TEST_NULL0);
-  Expect.isTrue(generated.contains("null"));
-  generated = compileAll(TEST_NULL1);
-  Expect.isTrue(generated.contains("null"));
+  asyncTest(() => compileAll(TEST_NULL0).then((generated) {
+    Expect.isTrue(generated.contains("null"));
+  }));
+
+  asyncTest(() => compileAll(TEST_NULL1).then((generated) {
+    Expect.isTrue(generated.contains("null"));
+  }));
 }