Adding isNotEmpty property to collection and string.

sdk/lib/collection/splay_tree.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.collection;
 
 /**
  * A node in a splay tree. It holds the sorting key and the left
  * and right children in the tree.
  */
@@ skipping 295 matching lines @@
     _addNewRoot(new _SplayTreeMapNode(key, value), comp);
     return value;
   }
 
   bool get isEmpty {
     // assert(!((_root == null) && (_count != 0)));
     // assert(!((_count == 0) && (_root != null)));
     return (_root == null);
   }
 
+  bool get isNotEmpty => !isEmpty;
+
   void forEach(void f(K key, V value)) {
     Iterator<_SplayTreeNode<K>> nodes =
         new _SplayTreeNodeIterator<K>(this);
     while (nodes.moveNext()) {
       _SplayTreeMapNode<K, V> node = nodes.current;
       f(node.key, node.value);
     }
   }
 
   int get length {
@@ skipping 203 matching lines @@
 class _SplayTreeValueIterator<K, V> extends _SplayTreeIterator<V> {
   _SplayTreeValueIterator(SplayTreeMap<K, V> map): super(map);
   V _getValue(_SplayTreeMapNode node) => node.value;
 }
 
 class _SplayTreeNodeIterator<K>
     extends _SplayTreeIterator<_SplayTreeNode<K>> {
   _SplayTreeNodeIterator(_SplayTree<K> map): super(map);
   _SplayTreeNode<K> _getValue(_SplayTreeNode node) => node;
 }