First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/field_type_simple_inferer_test.dart

Index: tests/compiler/dart2js/field_type_simple_inferer_test.dart
diff --git a/tests/compiler/dart2js/field_type_simple_inferer_test.dart b/tests/compiler/dart2js/field_type_simple_inferer_test.dart
index 1b5c87fe79fcb4efd944651c561077fa240e5845..6555838f9b43dec856c8e9f514a6856c1b878a87 100644
--- a/tests/compiler/dart2js/field_type_simple_inferer_test.dart
+++ b/tests/compiler/dart2js/field_type_simple_inferer_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 'dart:async';
 import 'package:expect/expect.dart';
 import '../../../sdk/lib/_internal/compiler/implementation/types/types.dart'
     show TypeMask;
@@ -15,12 +16,13 @@ void compileAndFind(String code,
                     bool disableInlining,
                     check(compiler, element)) {
   Uri uri = new Uri(scheme: 'source');
-  var compiler = compilerFor(code, uri);
-  compiler.runCompiler(uri);
-  compiler.disableInlining = disableInlining;
-  var cls = findElement(compiler, className);
-  var member = cls.lookupMember(buildSourceString(memberName));
-  return check(compiler.typesTask.typesInferrer, member);
+  MockCompiler compiler = compilerFor(code, uri);
+  compiler.runCompiler(uri).then((_) {
+    compiler.disableInlining = disableInlining;
+    var cls = findElement(compiler, className);
+    var member = cls.lookupMember(buildSourceString(memberName));
+    check(compiler.typesTask.typesInferrer, member);
+  });
 }
 
 const String TEST_1 = r"""