Example showing alternate async measurement solution

client/html/src/WindowWrappingImplementation.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
 // TODO(jacobr): define a base class containing the overlap between
 // this class and ElementEvents.
 class WindowEventsImplementation extends EventsImplementation
       implements WindowEvents {
   WindowEventsImplementation._wrap(_ptr) : super._wrap(_ptr);
 
   EventListenerList get abort() => _get('abort');
@@ skipping 784 matching lines @@
 
   void stop() {
     _ptr.stop();
   }
 
   void webkitCancelRequestAnimationFrame(int id) {
     _ptr.webkitCancelRequestAnimationFrame(id);
   }
 
   Point webkitConvertPointFromNodeToPage([Node node = null, Point p = null]) {
+    assert(_inMeasurementFrame);
     if (node === null) {
       if (p === null) {
         return LevelDom.wrapPoint(_ptr.webkitConvertPointFromNodeToPage());
       }
     } else {
       if (p === null) {
         return LevelDom.wrapPoint(_ptr.webkitConvertPointFromNodeToPage(LevelDom.unwrap(node)));
       } else {
         return LevelDom.wrapPoint(_ptr.webkitConvertPointFromNodeToPage(LevelDom.unwrap(node), LevelDom.unwrap(p)));
       }
     }
     throw "Incorrect number or type of arguments";
   }
 
   Point webkitConvertPointFromPageToNode([Node node = null, Point p = null]) {
+    assert(_inMeasurementFrame);
     if (node === null) {
       if (p === null) {
         return LevelDom.wrapPoint(_ptr.webkitConvertPointFromPageToNode());
       }
     } else {
       if (p === null) {
         return LevelDom.wrapPoint(_ptr.webkitConvertPointFromPageToNode(LevelDom.unwrap(node)));
       } else {
         return LevelDom.wrapPoint(_ptr.webkitConvertPointFromPageToNode(LevelDom.unwrap(node), LevelDom.unwrap(p)));
       }
     }
     throw "Incorrect number or type of arguments";
   }
 
   int webkitRequestAnimationFrame(RequestAnimationFrameCallback callback, [Element element = null]) {
     return _ptr.webkitRequestAnimationFrame(callback, LevelDom.unwrap(element));
   }
 
-  void requestLayoutFrame(TimeoutHandler callback) {
+  void requestMeasurementFrame(MeasurementCallback callback) {
     _addMeasurementFrameCallback(callback);
   }
 
+  bool get inMeasurementFrame() => _inMeasurementFrame;
+
   WindowEvents get on() {
     if (_on === null) {
       _on = new WindowEventsImplementation._wrap(_ptr);
     }
     return _on;
   }
 }