Add tests for generic methods in strong mode

tests/language_strong/generic_methods_tearoff_specialization_test.dart

+// 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.
+
+library generic_methods_tearoff_deferred_specialization2_test;
+
+import "package:expect/expect.dart";
+
+class A {
+  T fun<T>(T t) => t;
+}
+
+typedef Int2Int = int Function(int);
+typedef String2String = String Function(String);
+typedef Object2Object = Object Function(Object);
+typedef GenericMethod = T Function<T>(T);
+
+main() {
+  A a = new A();
+  Int2Int f = a.fun;
+  String2String g = a.fun;
+  Object2Object h = a.fun;
+  var generic = a.fun;
+
+  Expect.isTrue(f is Int2Int);
+  Expect.isTrue(f is! String2String);
+  Expect.isTrue(f is! Object2Object);
+  Expect.isTrue(f is! GenericMethod);
+
+  Expect.isTrue(g is! Int2Int);
+  Expect.isTrue(g is String2String);
+  Expect.isTrue(g is! Object2Object);
+  Expect.isTrue(g is! GenericMethod);
+
+  Expect.isTrue(h is! Int2Int);
+  Expect.isTrue(h is! String2String);
+  Expect.isTrue(h is Object2Object);
+  Expect.isTrue(g is! GenericMethod);
+
+  Expect.isTrue(generic is! Int2Int);
+  Expect.isTrue(generic is! String2String);
+  Expect.isTrue(generic is! Object2Object);
+  Expect.isTrue(generic is GenericMethod);
+}