Merge the work on Generic Types Reification from 'dart-lang/reify' repo

pkg/kernel/testcases/reify/reuse_type_variables_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.
+
+library reuse_type_variables_test;
+
+import 'test_base.dart';
+
+class X {}
+
+class Y {}
+
+class Z {}
+
+class C<T, U, V> {
+  foo() => new D<T, U, V>();
+  bar() => new E<T, U>();
+  hest() => new D<T, V, U>();
+}
+
+class D<T, U, V> {
+  baz() => new C<T, U, V>();
+}
+
+class E<T, U> {
+  qux() => new C<T, U, U>();
+}
+
+main() {
+  var c = new C<X, Y, Z>();
+  var d = c.foo();
+  expectTrue(d is D<X, Y, Z>);
+  d = c.hest();
+  expectTrue(d is! D<X, Y, Z>);
+  expectTrue(d is D<X, Z, Y>);
+  c = d.baz();
+  expectTrue(c is C<X, Z, Y>);
+  var e = c.bar();
+  expectTrue(e is E<X, Z>);
+  c = e.qux();
+  expectTrue(c is C<X, Z, Z>);
+}