Migrate test block 113 to Dart 2.0.

tests/language_strong/generic_function_bounds_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.
-
-import 'dart:math';
-import 'package:expect/expect.dart';
-
-void testInstantiateToBounds() {
-  f<T extends num, U extends T>() => [T, U];
-  g<T extends List<U>, U extends int>() => [T, U];
-  h<T extends num, U extends T>(T x, U y) => h.runtimeType.toString();
-
-  Expect.listEquals((f as dynamic)(), [num, num]);
-  Expect.equals((g as dynamic)().join('|'), 'List<int>|int');
-  Expect.equals((h as dynamic)(null, null),
-      '<T extends num, U extends T>(T, U) -> String');
-
-  i<T extends Iterable<T>>() => null;
-  j<T extends Iterable<S>, S extends T>() => null;
-  Expect.throws(
-      () => (i as dynamic)(), (e) => '$e'.contains('Instantiate to bounds'));
-  Expect.throws(
-      () => (j as dynamic)(), (e) => '$e'.contains('Instantiate to bounds'));
-}
-
-void testChecksBound() {
-  f<T extends num>(T x) => x;
-  Expect.equals((f as dynamic)(42), 42);
-  Expect.throws(() => (f as dynamic)('42'));
-
-  msg(t1, t2, tf) => Expect.throws(() => (f as dynamic)<Object>(42),
-      (e) => '$e' == 'type `Object` does not extend `num` of `T');
-
-  g<T extends U, U extends num>(T x, U y) => x;
-  Expect.equals((g as dynamic)(42.0, 100), 42.0);
-  Expect.throws(() => (g as dynamic)('hi', 100));
-  Expect.throws(() => (g as dynamic)<double, int>(42.0, 100),
-      (e) => '$e' == 'type `double` does not extend `int` of `T`.');
-
-  Expect.throws(() => (g as dynamic)<num, Object>(42.0, 100),
-      (e) => '$e' == 'type `Object` does not extend `num` of `U`.');
-}
-
-typedef G<U> = T Function<T extends U>(T x);
-
-void testSubtype() {
-  f<T extends num>(T x) => x + 2;
-
-  dynamic d = f;
-  Expect.equals(d(40.0), 42.0);
-  Expect.equals((f as G<int>)(40), 42);
-  Expect.equals((d as G<int>)(40), 42);
-  Expect.equals((f as G<double>)(40.0), 42.0);
-  Expect.equals((d as G<double>)(40.0), 42.0);
-
-  d as G<Null>;
-  Expect.throws(() => d as G);
-  Expect.throws(() => d as G<Object>);
-  Expect.throws(() => d as G<String>);
-}
-
-void testToString() {
-  // TODO(jmesserly): I don't think the cast on `y` should be required.
-  num f<T extends num, U extends T>(T x, U y) => min(x, y as num);
-  num g<T, U>(T x, U y) => max(x as num, y as num);
-  String h<T, U>(T x, U y) => h.runtimeType.toString();
-  Expect.equals(
-      f.runtimeType.toString(), '<T extends num, U extends T>(T, U) -> num');
-  Expect.equals(g.runtimeType.toString(), '<T, U>(T, U) -> num');
-  Expect.equals(h(42, 123.0), '<T, U>(T, U) -> String');
-}
-
-main() {
-  testInstantiateToBounds();
-  testToString();
-  testChecksBound();
-  testSubtype();
-}