Add language test with nested function typedef with two references to argument

tests/language/function_subtype_typearg5_test.dart

Index: tests/language/function_subtype_typearg5_test.dart
diff --git a/tests/language/function_subtype_typearg5_test.dart b/tests/language/function_subtype_typearg5_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..a20e4228a51e79509ba639bf9d7581347d9e6f1d
--- /dev/null
+++ b/tests/language/function_subtype_typearg5_test.dart
@@ -0,0 +1,55 @@
+// 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.
+
+// Check function subtyping of type arguments. These cases use typedefs as type
+// arguments, and the typedefs have type parameters that are used more than
+// once.
+
+import 'package:expect/expect.dart';
+
+typedef A F<A>(A arg1, A arg2);
+typedef B G<A,B>(B arg1, B arg2);
+
+typedef Set<A> FS<A>(Set<A> arg1, Set<A> arg2);
+
+@NoInline() @AssumeDynamic() dyn(x) => x;
+
+class CheckEnv<X, Y> {
+  test(bool intX) {
+    Expect.isTrue(<F<X>>[] is List<F>);
+    Expect.isTrue(<F<X>>[] is List<F<X>>);
+    Expect.isTrue(<F<X>>[] is List<G<Y,X>>);
+
+    Expect.isTrue(dyn(<F<X>>[]) is List<F>);
+    Expect.isTrue(dyn(<F<X>>[]) is List<F<X>>);
+    Expect.isTrue(dyn(<F<X>>[]) is List<G<Y,X>>);
+
+    Expect.isTrue(<F<X>>[] is! List<F<Y>>);
+    Expect.isTrue(<F<X>>[] is! List<G<X,Y>>);
+
+    Expect.isTrue(dyn(<F<X>>[]) is! List<F<Y>>);
+    Expect.isTrue(dyn(<F<X>>[]) is! List<G<X,Y>>);
+
+    Expect.isTrue(dyn(<FS<X>>[]) is List<FS>);
+    Expect.isTrue(dyn(<FS<X>>[]) is List<FS<X>>);
+    if (intX) {
+      Expect.isTrue(dyn(<FS<X>>[]) is List<FS<int>>);
+      Expect.isTrue(dyn(<FS<int>>[]) is List<FS<X>>);
+      Expect.isTrue(dyn(<FS<Y>>[]) is! List<FS<int>>);
+      Expect.isTrue(dyn(<FS<int>>[]) is! List<FS<Y>>);
+    }
+  }
+}
+
+
+
+main() {
+  Expect.isTrue(<F<int>>[] is List<F<int>>);
+  Expect.isTrue(dyn(<F<int>>[]) is List<F<int>>);
+  Expect.isTrue(<F<int>>[] is List<G<bool,int>>);
+  Expect.isTrue(dyn(<F<int>>[]) is List<G<bool,int>>);
+
+  new CheckEnv<int,String>().test(true);
+  new CheckEnv<String,int>().test(false);
+}