Handle type literals correctly with deferred loading and await.

tests/language/deferred_regression_28678_test.dart

+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// 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.
+
+// Test that await after deferred loading works as expected.
+
+import 'dart:async';
+import "package:expect/expect.dart";
+import 'deferred_regression_28678_lib.dart' deferred as lib;
+
+class A {
+  m() => "here";
+}
+
+f(a, b) => new Future.microtask(() {});
+
+class R {
+  Future test_deferred() async {
+    var a = new A();
+    await lib.loadLibrary();
+    await f(lib.Clazz, lib.v);
+    Expect.equals("here", a.m());
+  }
+}
+
+main() async {
+  await new R().test_deferred();
+}