Use JavaScript runtime semantics when constant folding.

pkg/fixnum/test/int_64_test.dart

 // Copyright (c) 2012, 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('int64test');
 #import('../fixnum.dart');
 
 void main() {
   testAdditive();
   testBitOps();
@@ skipping 406 matching lines @@
     new int64.fromInts(0x92341234, 0x45674567) >> 10);
   Expect.equals(new int64.fromInt(67108863),
     new int64.fromInts(0xFFFFFFF, 0xFFFFFFFF) >> 34);
   Expect.equals(new int64.fromInts(0x248d04, 0x8d1159d1),
     new int64.fromInts(0x92341234, 0x45674567).shiftRightUnsigned(10));
 
   for (int n = 0; n <= 66; n++) {
     Expect.equals(new int64.fromInt(-1), new int64.fromInt(-1) >> n);
   }
 
-  Expect.equals(new int64.fromInt(-1 << 5), new int64.fromInt(-1) << 5);
+  Expect.equals(new int64.fromInt(-32), new int64.fromInt(-1) << 5);
   Expect.equals(new int64.fromInt(-1), new int64.fromInt(-1) << 0);
   Expect.equals(-new int64.fromInts(0x40000000, 0x00000000),
     (new int64.fromInt(1) << 63) >> 1);
   Expect.equals(new int64.fromInt(0), (new int64.fromInt(-1) << 32) << 32);
   Expect.equals(int64.MIN_VALUE, int64.MIN_VALUE << 0);
   Expect.equals(new int64.fromInt(0), int64.MIN_VALUE << 1);
   Expect.equals(new int64.fromInts(0xfffffffc, 0x00000000),
     (-new int64.fromInts(8, 0)) >> 1);
   Expect.equals(new int64.fromInts(0x7ffffffc, 0x0),
     (-new int64.fromInts(8, 0)).shiftRightUnsigned(1));
@@ skipping 159 matching lines @@
   Expect.equals("777777777777777777777", int64.MAX_VALUE.toRadixString(8));
   Expect.equals("67404283172107811827", int64.MAX_VALUE.toRadixString(9));
   Expect.equals("9223372036854775807", int64.MAX_VALUE.toRadixString(10));
   Expect.equals("1728002635214590697", int64.MAX_VALUE.toRadixString(11));
   Expect.equals("41A792678515120367", int64.MAX_VALUE.toRadixString(12));
   Expect.equals("10B269549075433C37", int64.MAX_VALUE.toRadixString(13));
   Expect.equals("4340724C6C71DC7A7", int64.MAX_VALUE.toRadixString(14));
   Expect.equals("160E2AD3246366807", int64.MAX_VALUE.toRadixString(15));
   Expect.equals("7FFFFFFFFFFFFFFF", int64.MAX_VALUE.toRadixString(16));
 }