Make the AnimationController class future compatible, and also change it to

client/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 25 matching lines @@
   static final FRAMES_PER_SECOND = 60;
   static final MS_PER_FRAME = 1000 ~/ FRAMES_PER_SECOND;
   static final USE_INTERVALS = false;
 
   /** List of callbacks to be executed next animation frame. */
   List<CallbackData> _callbacks;
   int _intervalId;
   bool _isMobileSafari = false;
   Css _safariHackCss;
   int _frameCount = 0;
-  bool _webkitAnimationFrameMaybeAvailable = true;
+  bool _animationFrameMaybeAvailable = true;
 
   AnimationScheduler()
     : _callbacks = new List<CallbackData>() {
     if (_isMobileSafari) {
       // TODO(jacobr): find a better workaround for the issue that 3d transforms
       // sometimes don't render on iOS without forcing a layout.
       final element = new Element.tag('div');
       document.body.nodes.add(element);
       _safariHackCss = new Css(element.style);
       _safariHackCss.position = 'absolute';
@@ skipping 29 matching lines @@
       _setupInterval();
     }
   }
 
   void _setupInterval() {
     // Assert that we never schedule multiple frames at once.
     assert(_intervalId === null);
     if (USE_INTERVALS) {
       _intervalId = window.setInterval(_step, MS_PER_FRAME);
     } else {
-      if (_webkitAnimationFrameMaybeAvailable) {
+      if (_animationFrameMaybeAvailable) {
+        // First try to see if the browser supports the requestAnimationFrame API,
+        // and if that check fails, fall back to using WebKit/Mozilla/IE specific
+        // versions of the API.
         try {
           // TODO(jacobr): passing in document should not be required.
-          _intervalId = window.webkitRequestAnimationFrame(
+          _intervalId = window.requestAnimationFrame(

[Jacob, 2011/10/17 18:24:57]

This approach would cause multiple exceptions to be thrown every time an
animation frame is requested under Mozilla or IE.  To avoid this, we'd need to
track which animation frame callback worked and cache that Function.

               (int ignored) { _step(); }, document);
               // TODO(jacobr) fix this odd type error.
         } catch (var e) {
-          _webkitAnimationFrameMaybeAvailable = false;
+          try {
+            _intervalId = window.webkitRequestAnimationFrame(
+                (int ignored) { _step(); }, document);
+          } catch (var e) {
+            try {

[Jacob, 2011/10/17 18:24:57]

at some point, window.mozRequestAnimationFrame might work with dart:dom 
but at the moment the dart:dom bindings are WebKit specific so
window.mozRequestAnimationFrame will fail even on versions of Mozilla that
support it.

+              _intervalId = window.mozRequestAnimationFrame(
+                  (int ignored) { _step(); }, document);
+            } catch (e) {
+              try {
+                _intervalId = window.msRequestAnimationFrame(
+                    (int ignored) { _step(); }, document);
+              } catch (var e) {
+                _animationFrameMaybeAvailable = false;
+              }
+            }
+          }
         }
       }
-      if (!_webkitAnimationFrameMaybeAvailable) {
+      if (!_animationFrameMaybeAvailable) {
         _intervalId = window.setTimeout(() { _step(); }, MS_PER_FRAME);
       }
     }
   }
 
   void _step() {
     if (_callbacks.isEmpty()) {
       // Cancel the interval on the first frame where there aren't actually
       // any available callbacks.
       assert(_intervalId != null);
@@ skipping 40 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;
       _safariHackCss.left = '${offset}px';
     }
   }
 }