Change our 'is int' check to use Math.floor instead of a smi check.

pkg/intl/number_format.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("number_format");
 
 #import('dart:math');
 
 #import("intl.dart");
 #import("number_symbols.dart");
@@ skipping 138 matching lines @@
     var power = pow(10, _maximumFractionDigits);
     var intValue = number.truncate().toInt();
     var multiplied = (number * power).round();
     var fracValue = (multiplied - intValue * power).floor().toInt();
     var fractionPresent = _minimumFractionDigits > 0 || fracValue > 0;
 
     // On dartj2s the integer part may be large enough to be a floating
     // point value, in which case we reduce it until it is small enough
     // to be printed as an integer and pad the remainder with zeros.
     var paddingDigits = new StringBuffer();
-    while (intValue is! int) {
+    while ((intValue & 0x7fffffff) != intValue) {
       paddingDigits.add(symbols.ZERO_DIGIT);
       intValue = (intValue / 10).toInt();
     }
     var integerDigits = "${intValue}${paddingDigits}".charCodes();
     var digitLength = integerDigits.length;
 
     if (_hasPrintableIntegerPart(intValue)) {
       _pad(_minimumIntegerDigits - digitLength);
       for (var i = 0; i < digitLength; i++) {
         _addDigit(integerDigits[i]);
@@ skipping 93 matching lines @@
   }
 
   /**
    * Returns the suffix for [x] based on wether it's positive or negative.
    * In en_US there are no suffixes for positive or negative.
    */
   String _signSuffix(num x) {
     return x.isNegative() ? _negativeSuffix : _positiveSuffix;
   }
 }