Adding isNotEmpty property to collection and string.

sdk/lib/core/iterable.dart

 // Copyright (c) 2011, 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;
 
 /**
  * The [Iterable] interface allows to get an [Iterator] out of an
  * [Iterable] object.
  *
@@ skipping 144 matching lines @@
    * therefore be slow.
    */
   int get length;
 
   /**
    * Returns true if there is no element in this collection.
    */
   bool get isEmpty;
 
   /**
+   * Returns true if there is at least one element in this collection.
+   */
+  bool get isNotEmpty;
+
+  /**
    * Returns an [Iterable] with at most [n] elements.
    *
    * The returned [Iterable] may contain fewer than [n] elements, if `this`
    * contains fewer than [n] elements.
    */
   Iterable<E> take(int n);
 
   /**
    * Returns an [Iterable] that stops once [test] is not satisfied anymore.
    *
@@ skipping 123 matching lines @@
  */
 abstract class BidirectionalIterator<E> implements Iterator<E> {
   /**
    * Move back to the previous element.
    *
    * Returns true and updates [current] if successful. Returns false
    * and sets [current] to null if there is no previous element.
    */
   bool movePrevious();
 }