Mark code when it instantiates an unloaded deferred type

tests/language/regress_22443_test.dart

Index: tests/language/regress_22443_test.dart
===================================================================
--- tests/language/regress_22443_test.dart	(revision 0)
+++ tests/language/regress_22443_test.dart	(working copy)
@@ -0,0 +1,23 @@
+// Copyright (c) 2015, 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.
+
+import 'regress_22443_lib.dart' deferred as D;
+import 'package:expect/expect.dart';
+
+int fooCount = 0;
+
+foo() {
+  fooCount++;
+  return new D.LazyClass();
+}
+
+main() {
+  var caughtIt = false;
+  try { foo(); } catch (e) { caughtIt = true; };
+  D.loadLibrary().then((_) {
+    foo();
+    Expect.isTrue(caughtIt);
+    Expect.equals(2, fooCount);
+  });
+}