Import rasta tests.

pkg/fasta/test/rasta/generic_factory.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.md file.
+
+class C1 {
+}
+
+class C2 {
+}
+
+class C3 {
+}
+
+class A<T> {
+  A.internal();
+
+  factory A.a() = B<T>.a;
+  factory A.b() = B<C1>.a;
+  factory A.c() = Missing;
+}
+
+class B<S> extends A<S> {
+  B.internal()
+      : super.internal();
+
+  factory B.a() = C<S>;
+  factory B.b() = C<C2>;
+}
+
+class C<U> extends B<U> {
+  C()
+      : super.internal();
+}
+
+main() {
+  new A<C3>.a();
+  new A<C3>.b();
+  new B<C3>.a();
+  new B<C3>.b();
+  new A<C3>.c();
+}