Add num.sign getter.

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 74 matching lines @@
   bool operator ==(other) {
     if (other is num) {
       return other._equalToInteger(this);
     }
     return false;
   }
   bool _equalToInteger(int other) native "Integer_equalToInteger";
   int abs() {
     return this < 0 ? -this : this;
   }
+  int get sign {
+    return (this > 0) ? 1 : (this < 0) ? -1 : 0;
+  }
   bool get isEven => ((this & 1) == 0);
   bool get isOdd => !isEven;
   bool get isNaN => false;
   bool get isNegative => this < 0;
   bool get isInfinite => false;
   bool get isFinite => true;
 
   int toUnsigned(int width) {
     return this & ((1 << width) - 1);
   }
@@ skipping 229 matching lines @@
     } else {
       return 0;
     }
   }
   int _shlFromInt(int other) native "Bigint_shlFromInt";
 
   int pow(int exponent) {
     throw "Bigint.pow not implemented";
   }
 }