Make 'where' lazy.

samples/swarm/swarm_ui_lib/base/AnimationScheduler.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.
 
 typedef void AnimationCallback(num currentTime);
 
 class CallbackData {
   final AnimationCallback callback;
   final num minTime;
   int id;
@@ skipping 45 matching lines @@
       _safariHackStyle.position = 'absolute';
     }
   }
 
   /**
    * Cancel the pending callback matching the specified [id].
    * This is not heavily optimized as typically users don't cancel animation
    * frames.
    */
   void cancelRequestAnimationFrame(int id) {
-    _callbacks = _callbacks.where((CallbackData e) => e.id != id);
+    _callbacks = _callbacks.where((CallbackData e) => e.id != id).toList();

[Lasse Reichstein Nielsen, 2012/11/20 11:44:57]

We want a mutating method on Collection: removeAllMatching.

[floitsch, 2012/11/28 13:49:38]

Agreed. Not sure where, but it is a common task.

   }
 
   /**
    * Schedule [callback] to execute at the next animation frame that occurs
    * at or after [minTime].  If [minTime] is not specified, the first available
    * animation frame is used.  Returns an id that can be used to cancel the
    * pending callback.
    */
   int requestAnimationFrame(AnimationCallback callback,
                             [Element element = null,
@@ skipping 80 matching lines @@
     _frameCount++;
     if (_isMobileSafari) {
       // Hack to work around an iOS bug where sometimes animations do not
       // render if only webkit transforms were modified.
       // TODO(jacobr): find a cleaner workaround.
       int offset = _frameCount % 2;
       _safariHackStyle.left = '${offset}px';
     }
   }
 }