Capture instantiator in async function when required to check result type.

tests/language/regress_26668_test.dart

+// Copyright (c) 2016, 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.
+// Tests that the VM does not crash on weird corner cases of class Math.

[hausner, 2016/06/10 17:24:56]

Comment is probably a left-over from another test. I'll fix it in a separate CL.

+
+import 'dart:async';
+
+main() async {
+  var myClass = new CustomClass<int>();
+  await myClass.processData();
+}
+
+class CustomClass<T> {
+  Future<T> processData() async {
+    return 0;
+  }
+}
+