First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/simple_inferrer_unregister_call_test.dart

Index: tests/compiler/dart2js/simple_inferrer_unregister_call_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_unregister_call_test.dart b/tests/compiler/dart2js/simple_inferrer_unregister_call_test.dart
index 0341df421f9cea22ca3cfaa626fbcfa510fa159b..6d5ef4d80f4f3a5d9a7414cea44674e7b8010e7b 100644
--- a/tests/compiler/dart2js/simple_inferrer_unregister_call_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_unregister_call_test.dart
@@ -32,14 +32,15 @@ main() {
 void main() {
   Uri uri = new Uri(scheme: 'source');
   var compiler = compilerFor(TEST, uri);
-  compiler.runCompiler(uri);
-  var typesInferrer = compiler.typesTask.typesInferrer;
+  compiler.runCompiler(uri).then((_) {
+    var typesInferrer = compiler.typesTask.typesInferrer;
 
-  checkReturnInClass(String className, String methodName, type) {
-    var cls = findElement(compiler, className);
-    var element = cls.lookupLocalMember(buildSourceString(methodName));
-    Expect.equals(type, typesInferrer.internal.returnTypeOf[element]);
-  }
+    checkReturnInClass(String className, String methodName, type) {
+      var cls = findElement(compiler, className);
+      var element = cls.lookupLocalMember(buildSourceString(methodName));
+      Expect.equals(type, typesInferrer.internal.returnTypeOf[element]);
+    }
 
-  checkReturnInClass('A', '+', typesInferrer.intType);
+    checkReturnInClass('A', '+', typesInferrer.intType);
+  });
 }