Fixes obo error in javascript int checking.

runtime/lib/integers.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.
 
 // TODO(srdjan): fix limitations.
 // - shift amount must be a Smi.
 class _IntegerImplementation {
   factory _IntegerImplementation._uninstantiable() {
     throw new UnsupportedError(
         "_IntegerImplementation can only be allocated by the VM");
@@ skipping 81 matching lines @@
   bool get isEven => ((this & 1) == 0);
   bool get isOdd => !isEven;
   bool get isNaN => false;
   bool get isNegative => this < 0;
   bool get isInfinite => false;
 
   int compareTo(num other) {
     final int EQUAL = 0, LESS = -1, GREATER = 1;
     if (other is double) {
       // TODO(floitsch): the following locals should be 'const'.
-      int MAX_EXACT_INT_TO_DOUBLE = 9007199254740991;  // 2^53 - 1.
+      int MAX_EXACT_INT_TO_DOUBLE = 9007199254740992;  // 2^53.
       int MIN_EXACT_INT_TO_DOUBLE = -MAX_EXACT_INT_TO_DOUBLE;
       double d = other;
       if (d.isInfinite) {
         return d == double.NEGATIVE_INFINITY ? GREATER : LESS;
       }
       if (d.isNaN) {
         return LESS;
       }
       if (MIN_EXACT_INT_TO_DOUBLE <= this && this <= MAX_EXACT_INT_TO_DOUBLE) {
         // Let the double implementation deal with -0.0.
@@ skipping 182 matching lines @@
     } else {
       return 0;
     }
   }
   int _shlFromInt(int other) native "Bigint_shlFromInt";
 
   int pow(int exponent) {
     throw "Bigint.pow not implemented";
   }
 }