Add tests for generic methods in strong mode

tests/language_strong/generic_methods_local_variable_declaration_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_local_variable_declaration_test;
+
+import "package:expect/expect.dart";
+
+abstract class Generator<T> {
+  T generate();
+}
+
+class A implements Generator<A> {
+  @override

[karlklose, 2017/03/09 09:17:00]

Consider leaving out '@override'.

[floitsch, 2017/03/09 11:27:17]

Also note that not writing any type here would infer the type from super.
You could just write `generate() {`.

[Dmitry Stefantsov, 2017/03/10 13:21:54]

Thanks!

[Dmitry Stefantsov, 2017/03/10 13:21:54]

Done.

+  A generate() {
+    return new A();
+  }
+
+  @override
+  String toString() => "instance of A";
+}
+
+class B implements Generator<B> {
+  @override
+  B generate() {
+    return new B();
+  }
+
+  @override
+  String toString() => "instance of B";
+}
+
+String fun<T extends Generator<T>>(T t) {
+  T another = t.generate();
+  String anotherName = "$another";
+
+  Expect.isTrue(another is T);
+  Expect.isTrue(anotherName is! T); // fails if T is substituted with dynamic

[floitsch, 2017/03/09 11:27:17]

Start comments with uppercase and finish them with ".".

[eernst, 2017/03/09 14:55:02]

This is again a check that seems to be justified solely because it will force
Dart 1 executions to fail, so it should be treated like other checks of the same
kind (possibly removing it).

[Dmitry Stefantsov, 2017/03/10 13:21:54]

That's right. It's Dart 1 specific, so I'm removing it.

[Dmitry Stefantsov, 2017/03/10 13:21:54]

Done.

+
+  return anotherName;
+}
+
+main() {
+  A a = new A();
+  B b = new B();
+
+  Expect.isTrue(fun<A>(a) == "instance of A");
+  Expect.isTrue(fun<B>(b) == "instance of B");
+}