Migrate test block 3 to Dart 2.0.

tests/corelib/collection_from_test.dart

-// Copyright (c) 2011, 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 collection.from.test;
-
-import "package:expect/expect.dart";
-import 'dart:collection' show Queue;
-
-class CollectionFromTest {
-  static testMain() {
-    var set = new Set<int>();
-    set.add(1);
-    set.add(2);
-    set.add(4);
-    check(set, new List<int>.from(set));
-    check(set, new List.from(set));
-    check(set, new Queue<int>.from(set));
-    check(set, new Queue.from(set));
-    check(set, new Set<int>.from(set));
-    check(set, new Set.from(set));
-  }
-
-  static check(Iterable initial, Iterable other) {
-    Expect.equals(3, initial.length);
-    Expect.equals(initial.length, other.length);
-
-    int initialSum = 0;
-    int otherSum = 0;
-
-    initial.forEach((e) {
-      initialSum += e;
-    });
-    other.forEach((e) {
-      otherSum += e;
-    });
-    Expect.equals(4 + 2 + 1, otherSum);
-    Expect.equals(otherSum, initialSum);
-  }
-}
-
-main() {
-  CollectionFromTest.testMain();
-}