Add num.sign getter.

sdk/lib/core/int.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.
 
 part of dart.core;
 
 /**
  * An arbitrarily large integer.
  *
  * **Note:** When compiling to JavaScript, integers are
@@ skipping 178 matching lines @@
    */
   int operator -();
 
   /**
    * Returns the absolute value of this integer.
    *
    * For any integer `x`, the result is the same as `x < 0 ? -x : x`.
    */
   int abs();
 
+  /**
+   * Returns the sign of this integer.
+   *
+   * Returns 0 for zero, -1 for values less than zero and
+   * +1 for values greater than zero.
+   */
+  int get sign;
+
   /** Returns `this`. */
   int round();
 
   /** Returns `this`. */
   int floor();
 
   /** Returns `this`. */
   int ceil();
 
   /** Returns `this`. */
@@ skipping 52 matching lines @@
    * value is used instead. If no [onError] is provided, a [FormatException]
    * is thrown.
    *
    * The [onError] function is only invoked if [source] is a [String]. It is
    * not invoked if the [source] is, for example, `null`.
    */
   external static int parse(String source,
                             { int radix,
                               int onError(String source) });
 }