Reapply "Convert HashSet, LinkedHashSet to factory methods and custom implementations."

tests/corelib/hash_set_test.dart

 // Copyright (c) 2013, 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.
 
 // Tests of hash set behavior, with focus in iteration and concurrent
 // modification errors.
 
 library hash_map2_test;
 import "package:expect/expect.dart";
 import 'dart:collection';
 
 testSet(Set newSet(), Set newSetFrom(Set from)) {
+
   Set gen(int from, int to) =>
       new Set.from(new Iterable.generate(to - from, (n) => n + from));
 
   bool odd(int n) => (n & 1) == 1;
   bool even(int n) => (n & 1) == 0;
 
   {  // Test growing to largish capacity.
     Set set = newSet();
 
     for (int i = 0; i < 256; i++) {
       set.add(i);
     }
+
     set.addAll(gen(256, 512));
     set.addAll(newSetFrom(gen(512, 1000)));
     Expect.equals(1000, set.length);
 
     // Remove half.
     for (int i = 0; i < 1000; i += 2) set.remove(i);
     Expect.equals(500, set.length);
     Expect.isFalse(set.any(even));
     Expect.isTrue(set.every(odd));
 
@@ skipping 191 matching lines @@
 
 class BadHashCode {
   static int idCounter = 0;
   final int id;
   BadHashCode() : id = idCounter++;
   int get hashCode => 42;
   // operator == is identity.
   // Can't make a bad compareTo that isn't invalid.
   int compareTo(BadHashCode other) => id - other.id;
 }