Add missing test from previous CL.

pkg/front_end/test/fasta/type_variable_as_super.dart

Index: pkg/front_end/test/fasta/type_variable_as_super.dart
diff --git a/pkg/front_end/test/fasta/type_variable_as_super.dart b/pkg/front_end/test/fasta/type_variable_as_super.dart
new file mode 100644
index 0000000000000000000000000000000000000000..a9cb1e7e4d343a28e8026a87886b8fb3cc742683
--- /dev/null
+++ b/pkg/front_end/test/fasta/type_variable_as_super.dart
@@ -0,0 +1,19 @@
+// 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.
+
+abstract class A<T> extends T {
+}
+
+abstract class B<T> extends T {
+  B();
+}
+
+class C<T> extends T {
+}
+
+main() {
+  new A();
+  new B();
+  new C();
+}