Add tests for generic methods in strong mode

tests/language_strong/generic_methods_overriding_test.dart

Index: tests/language_strong/generic_methods_overriding_test.dart
diff --git a/tests/language_strong/generic_methods_overriding_test.dart b/tests/language_strong/generic_methods_overriding_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..2de07fc2576d3628043e40e6acdb545afb1850eb
--- /dev/null
+++ b/tests/language_strong/generic_methods_overriding_test.dart
@@ -0,0 +1,62 @@
+// 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.
+
+// Test that generic methods can be overloaded (a) with widened type bounds, and
+// (b) using the bound as the type of the parameter in the overloaded method.
+
+library generic_methods_overriding_test;
+
+import "package:expect/expect.dart";
+
+class X {}
+
+class Y extends X {}
+
+class Z extends Y {}
+
+class C {
+  String fun<T extends Y>(T t) => "C";
+}
+
+class D extends C {
+  String fun<T extends X>(T t) => "D"; /// 01: compile-time error
+  String fun<T extends Y>(T t) => "D"; /// 02: ok
+}
+
+class E extends C {
+  String fun<T>(Y y) => "E"; /// 03: compile-time error
+  String fun<T extends Y>(Y y) => "E"; /// 04: ok
+}
+
+class F extends C {
+  String foobar(Z z) {
+    return "FZ";
+  }
+
+  String fun<T extends Y>(T t) {
+    if (t is Z) {
+      return this.foobar(t as Z); /// 05: ok
+      return this.foobar(t); /// 06: ok
+    }
+    return "FY";
+  }
+}
+
+main() {
+  Y y = new Y();
+  Z z = new Z();
+
+  C c = new C();
+  D d = new D();
+  E e = new E();
+  F f = new F();
+
+  Expect.equals(c.fun<Y>(y), "C");
+  Expect.equals(d.fun<Y>(y), "D"); /// 02: continued
+  Expect.equals(e.fun<Y>(y), "E"); /// 04: continued
+  Expect.equals(f.fun<Y>(y), "FY"); /// 05: continued
+  Expect.equals(f.fun<Z>(z), "FZ"); /// 05: continued
+  Expect.equals(f.fun<Y>(y), "FY"); /// 06: continued
+  Expect.equals(f.fun<Z>(z), "FZ"); /// 06: continued
+}