Add isFinite getter to num.

sdk/lib/core/num.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 integer or floating-point number.
  *
  * It is a compile-time error for any type other than [int] or [double]
@@ skipping 124 matching lines @@
 
   /** Relational less than or equal operator. */
   bool operator <=(num other);
 
   /** Relational greater than operator. */
   bool operator >(num other);
 
   /** Relational greater than or equal operator. */
   bool operator >=(num other);
 
+  /** True if the number is the double Not-a-Number value; otherwise, false. */
   bool get isNaN;
 
+  /**
+   * True if the number is negative; otherwise, false.
+   *
+   * Negative numbers are those less than zero, and the double `-0.0`.
+   */
   bool get isNegative;
 
+  /**
+   * True if the number is positive infinity or negative infinity; otherwise,
+   * false.
+   */
   bool get isInfinite;
 
+  /**
+   * True if the number is finite; otherwise, false.
+   *
+   * The only non-finite numbers are NaN, positive infinitity and
+   * negative infinity.
+   */
+  bool get isFinite;
+
   /** Returns the absolute value of this [num]. */
   num abs();
 
   /**
    * Returns the integer closest to `this`.
    *
    * Rounds away from zero when there is no closest integer:
    *  [:(3.5).round() == 4:] and [:(-3.5).round() == -4:].
    *
    * If `this` is not finite (`NaN` or infinity), throws an [UnsupportedError].
@@ skipping 174 matching lines @@
    *
    * Note: the conversion may round the output if the returned string
    * is accurate enough to uniquely identify the input-number.
    * For example the most precise representation of the [double] `9e59` equals
    * `"899999999999999918767229449717619953810131273674690656206848"`, but
    * this method returns the shorter (but still uniquely identifying) `"9e59"`.
    *
    */
   String toString();
 }