Adding isNotEmpty property to collection and string.

sdk/lib/collection/iterable.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;
 
 /**
  * This [Iterable] mixin implements all [Iterable] members except `iterator`.
  *
  * All other methods are implemented in terms of `iterator`.
@@ skipping 77 matching lines @@
     int count = 0;
     Iterator it = iterator;
     while (it.moveNext()) {
       count++;
     }
     return count;
   }
 
   bool get isEmpty => !iterator.moveNext();
 
+  bool get isNotEmpty => !isEmpty;
+
   Iterable<E> take(int n) {
     return new TakeIterable<E>(this, n);
   }
 
   Iterable<E> takeWhile(bool test(E value)) {
     return new TakeWhileIterable<E>(this, test);
   }
 
   Iterable<E> skip(int n) {
     return new SkipIterable<E>(this, n);
@@ skipping 172 matching lines @@
     int count = 0;
     Iterator it = iterator;
     while (it.moveNext()) {
       count++;
     }
     return count;
   }
 
   bool get isEmpty => !iterator.moveNext();
 
+  bool get isNotEmpty => !isEmpty;
+
   Iterable<E> take(int n) {
     return new TakeIterable<E>(this, n);
   }
 
   Iterable<E> takeWhile(bool test(E value)) {
     return new TakeWhileIterable<E>(this, test);
   }
 
   Iterable<E> skip(int n) {
     return new SkipIterable<E>(this, n);
@@ skipping 75 matching lines @@
   E elementAt(int index) {
     if (index is! int || index < 0) throw new RangeError.value(index);
     int remaining = index;
     for (E element in this) {
       if (remaining == 0) return element;
       remaining--;
     }
     throw new RangeError.value(index);
   }
 }