Adding isNotEmpty property to collection and string.

sdk/lib/_internal/compiler/implementation/lib/constant_map.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 _js_helper;
 
 // This class has no constructor. This is on purpose since the instantiation
 // is shortcut by the compiler.
 class ConstantMap<V> implements Map<String, V> {
   final int length;
@@ skipping 22 matching lines @@
   Iterable<String> get keys {
     return new _ConstantMapKeyIterable(this);
   }
 
   Iterable<V> get values {
     return _keys.map((String key) => this[key]);
   }
 
   bool get isEmpty => length == 0;
 
+  bool get isNotEmpty => !isEmpty;
+
   String toString() => Maps.mapToString(this);
 
   _throwUnmodifiable() {
     throw new UnsupportedError("Cannot modify unmodifiable Map");
   }
   void operator []=(String key, V val) => _throwUnmodifiable();
   V putIfAbsent(String key, V ifAbsent()) => _throwUnmodifiable();
   V remove(String key) => _throwUnmodifiable();
   void clear() => _throwUnmodifiable();
 }
@@ skipping 13 matching lines @@
     return super[key];
   }
 }
 
 class _ConstantMapKeyIterable extends IterableBase<String> {
   ConstantMap _map;
   _ConstantMapKeyIterable(this._map);
 
   Iterator<String> get iterator => _map._keys.iterator;
 }