Adding isNotEmpty property to collection and string.

sdk/lib/io/buffer_list.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.io;
 
 /**
  * Utility class that can fast concatenate [List<int>]s of bytes. Use
  * [readBytes] to get the final buffer.
  */
@@ skipping 65 matching lines @@
    * Returns the total number of bytes in the buffer.
    */
   int get length => _length;
 
   /**
    * Returns whether the buffer list is empty.
    */
   bool get isEmpty => _length == 0;
 
   /**
+   * Returns whether the buffer list is not empty.
+   */
+  bool get isNotEmpty => !isEmpty;
+
+  /**
    * Clears the content of the buffer list.
    */
   void clear() {
     _length = 0;
     _buffer = null;
   }
 
   int _length;  // Total number of bytes in the buffer.
   Uint8List _buffer;  // Internal buffer.
 }