Make test compatible with dart2js integer semantics.

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.
 //
 // VMOptions=
 // VMOptions=--use_compact_hash=false
 
 // 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';
+import 'dart:math' as math;
 
 testSet(Set newSet(), Set newSetFrom(Iterable 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.
@@ skipping 229 matching lines @@
     Expect.identical(1, set.lookup(1.0));
     set.add(-0.0);
     Expect.identical(-0.0, set.lookup(0.0));
   }
 
   {  // Test special hash codes
     Set set = newSet();
     List keys = [];
     // Powers of two
     for (int i = 65; i >= 2; --i) {
-      keys.add(new Mutable(1 << i));
+      keys.add(new Mutable(math.pow(2, i)));
     }
     for (var key in keys) {
       Expect.isTrue(set.add(key));
     }
     for (var key in keys) {
       Expect.isTrue(set.contains(key));
     }
   }
 }
 
@@ skipping 66 matching lines @@
   // Can't make a bad compareTo that isn't invalid.
   int compareTo(BadHashCode other) => id - other.id;
 }
 
 class Mutable {
   int id;
   Mutable(this.id);
   int get hashCode => id;
   bool operator==(other) => other is Mutable && id == other.id;
 }