First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/class_order_test.dart

Index: tests/compiler/dart2js/class_order_test.dart
diff --git a/tests/compiler/dart2js/class_order_test.dart b/tests/compiler/dart2js/class_order_test.dart
index a4cc29e48ab11ebce029daf77157858b068ecf71..90c62d50795099335ce8d2c7aa9ff34e26a4c7d4 100644
--- a/tests/compiler/dart2js/class_order_test.dart
+++ b/tests/compiler/dart2js/class_order_test.dart
@@ -35,9 +35,11 @@ main() {
   // we just verify that their members are in the correct order.
   RegExp regexp = new RegExp(r"foo\$0?:(.|\n)*bar\$0:(.|\n)*gee\$0:");
 
-  String generated = compileAll(TEST_ONE);
-  Expect.isTrue(regexp.hasMatch(generated));
+  compileAll(TEST_ONE).then((generated) {
+    Expect.isTrue(regexp.hasMatch(generated));
+  });
 
-  generated = compileAll(TEST_TWO);
-  Expect.isTrue(regexp.hasMatch(generated));
+  compileAll(TEST_TWO).then((generated) {
+    Expect.isTrue(regexp.hasMatch(generated));
+  });
 }