Fixes obo error in javascript int checking.

tests/standalone/javascript_int_overflow_literal_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=--throw_on_javascript_int_overflow
 
 
 import "package:expect/expect.dart";
 
 int literals() {
-  var okay_literal = 0x1FFFFFFFFFFFFF;
-  var too_big_literal = 0x20000000000000;  /// 01: compile-time error
+  var okay_literal = 0x20000000000000;
+  var too_big_literal = 0x20000000000001;  /// 01: compile-time error
   return okay_literal;
 }
 
 main() {
-  Expect.equals(0x1FFFFFFFFFFFFF, literals());
+  Expect.equals(0x20000000000000, literals());
 }