Make generator argument to Iterable.generate optional.

sdk/lib/internal/iterable.dart

 // Copyright (c) 2011, 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._internal;
 
 /**
  * Marker interface for [Iterable] subclasses that have an efficient
  * [length] implementation.
  */
@@ skipping 695 matching lines @@
 
   Iterable<E> skip(int count) {
     if (count < 0) throw new RangeError.value(count);
     return this;
   }
 
   Iterable<E> skipWhile(bool test(E element)) => this;
 
   Iterable<E> take(int count) {
     if (count < 0) throw new RangeError.value(count);
-    this;
+    return this;
   }
 
   Iterable<E> takeWhile(bool test(E element)) => this;
 
   List toList({ bool growable: true }) => growable ? <E>[] : new List<E>(0);
 
   Set toSet() => new Set<E>();
 }
 
 /** The always empty iterator. */
@@ skipping 431 matching lines @@
 
   static Set setDifference(Set set, Set other, Set result) {
     for (var element in set) {
       if (!other.contains(element)) {
         result.add(element);
       }
     }
     return result;
   }
 }