Adding isNotEmpty property to collection and string.

sdk/lib/_internal/compiler/implementation/lib/js_array.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 _interceptors;
 
 /**
  * The interceptor class for [List]. The compiler recognizes this
  * class as an interceptor, and changes references to [:this:] to
  * actually use the receiver of the method, which is generated as an extra
@@ skipping 229 matching lines @@
 
   bool contains(E other) {
     for (int i = 0; i < length; i++) {
       if (other == this[i]) return true;
     }
     return false;
   }
 
   bool get isEmpty => length == 0;
 
+  bool get isNotEmpty => !isEmpty;
+
   String toString() => ToString.iterableToString(this);
 
   List<E> toList({ bool growable: true }) =>
       new List<E>.from(this, growable: growable);
 
   Set<E> toSet() => new Set<E>.from(this);
 
   Iterator<E> get iterator => new ListIterator<E>(this);
 
   int get hashCode => Primitives.objectHashCode(this);
@@ skipping 25 matching lines @@
   }
 }
 
 /**
  * Dummy subclasses that allow the backend to track more precise
  * information about arrays through their type.
  */
 class JSMutableArray extends JSArray implements JSMutableIndexable {}
 class JSFixedArray extends JSMutableArray {}
 class JSExtendableArray extends JSMutableArray {}