First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/concrete_type_inference_test.dart

Index: tests/compiler/dart2js/concrete_type_inference_test.dart
diff --git a/tests/compiler/dart2js/concrete_type_inference_test.dart b/tests/compiler/dart2js/concrete_type_inference_test.dart
index 71d8488cba6a439e1ab23c7282a375e7623205b4..fefb7a67a1be395c1c28c4f56e7cca149830d801 100644
--- a/tests/compiler/dart2js/concrete_type_inference_test.dart
+++ b/tests/compiler/dart2js/concrete_type_inference_test.dart
@@ -2,17 +2,19 @@
 // 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 'compiler_helper.dart';
 import 'parser_helper.dart';
 
-void compileAndFind(String code, String name,
+Future compileAndFind(String code, String name,
                     check(compiler, element)) {
   Uri uri = new Uri(scheme: 'source');
-  var compiler = compilerFor(code, uri);
-  compiler.runCompiler(uri);
-  var element = findElement(compiler, name);
-  return check(compiler, element);
+  MockCompiler compiler = compilerFor(code, uri);
+  compiler.runCompiler(uri).then((_) {
+    var element = findElement(compiler, name);
+    return check(compiler, element);
+  });
 }
 
 void checkPrintType(String expression, checkType(compiler, type)) {