Fix type argument finalization of some recursive generic types (fixes #29949).

tests/language/regress_29949_test.dart

Index: tests/language/regress_29949_test.dart
diff --git a/tests/language/regress_29949_test.dart b/tests/language/regress_29949_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..8685fae643cde573c16f09cbbf9c2d85f6226506
--- /dev/null
+++ b/tests/language/regress_29949_test.dart
@@ -0,0 +1,15 @@
+// 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 S {}
+
+abstract class M<T> {}
+
+abstract class N<T> {}
+
+class C<T> extends S with M<C<T>>, N<C<T>> {}
+
+main() {
+  new C<int>();
+}

[siva, 2017/06/21 21:46:45]

You may see failures in other tools (dart2js/ddc ec.) on this test, not sure.