First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/class_codegen_test.dart

Index: tests/compiler/dart2js/class_codegen_test.dart
diff --git a/tests/compiler/dart2js/class_codegen_test.dart b/tests/compiler/dart2js/class_codegen_test.dart
index b4e72c1996424bdc3a07ae9bbe0c5ac6071e8aa4..2cff73b3f850d23c943015a0fd5167ac179cc054 100644
--- a/tests/compiler/dart2js/class_codegen_test.dart
+++ b/tests/compiler/dart2js/class_codegen_test.dart
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 // Test that parameters keep their names in the output.
 
+import 'dart:async';
 import "package:expect/expect.dart";
 import 'compiler_helper.dart';
 import 'parser_helper.dart';
@@ -64,9 +65,10 @@ main() {
 """;
 
 twoClasses() {
-  String generated = compileAll(TEST_ONE);
-  Expect.isTrue(generated.contains('A: {"": "Object;"'));
-  Expect.isTrue(generated.contains('B: {"": "Object;"'));
+  return compileAll(TEST_ONE).then((generated) {
+    Expect.isTrue(generated.contains('A: {"": "Object;"'));
+    Expect.isTrue(generated.contains('B: {"": "Object;"'));
+  });
 }
 
 subClass() {
@@ -75,18 +77,20 @@ subClass() {
     Expect.isTrue(generated.contains('B: {"": "A;"'));
   }
 
-  checkOutput(compileAll(TEST_TWO));
-  checkOutput(compileAll(TEST_THREE));
+  compileAll(TEST_TWO).then(checkOutput);
+  compileAll(TEST_THREE).then(checkOutput);
 }
 
 fieldTest() {
-  String generated = compileAll(TEST_FOUR);
-  Expect.isTrue(generated.contains(r"""B: {"": "A;y,z,x", static:"""));
+  return compileAll(TEST_FOUR).then((generated) {
+    Expect.isTrue(generated.contains(r"""B: {"": "A;y,z,x", static:"""));
+  });
 }
 
 constructor1() {
-  String generated = compileAll(TEST_FIVE);
-  Expect.isTrue(generated.contains(new RegExp(r"new [$a-z]+\.A\(a\);")));
+  return compileAll(TEST_FIVE).then((generated) {
+    Expect.isTrue(generated.contains(new RegExp(r"new [$a-z]+\.A\(a\);")));
+  });
 }
 
 main() {