Example showing alternate async measurement solution

client/html/release/html.dart

Index: client/html/release/html.dart
diff --git a/client/html/release/html.dart b/client/html/release/html.dart
index 7cde3370964ea4f173c2e83ae43aa09982283766..55763d5c704a1b5eac6e89b0ad910fac69edd551 100644
--- a/client/html/release/html.dart
+++ b/client/html/release/html.dart
@@ -11294,7 +11294,7 @@ interface DeviceOrientationEvent extends Event default DeviceOrientationEventWra
 
   num get gamma();
 }
-// 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.
 
@@ -11355,9 +11355,11 @@ interface Document extends Element /*, common.NodeSelector */ {
 
   String get webkitVisibilityState();
 
-  Future<Range> caretRangeFromPoint([int x, int y]);
+  /** Only call when [window.inMeasurementFrame] is true. */
+  Range caretRangeFromPoint([int x, int y]);
 
-  Future<Element> elementFromPoint([int x, int y]);
+  /** Only call when [window.inMeasurementFrame] is true. */
+  Element elementFromPoint([int x, int y]);
 
   bool execCommand([String command, bool userInterface, String value]);
 
@@ -11380,8 +11382,6 @@ interface Document extends Element /*, common.NodeSelector */ {
   void set manifest(String value);
 
   DocumentEvents get on();
-
-  Future<ElementRect> get rect();
 }
 // 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
@@ -11432,7 +11432,7 @@ interface DOMApplicationCache extends EventTarget {
 
   DOMApplicationCacheEvents get on();
 }
-// 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.
 
@@ -11442,10 +11442,6 @@ interface ElementList extends List<Element> {
   // TODO(jacobr): add insertAt
 }
 
-class DeferredElementRect {
-  // TODO(jacobr)
-}
-
 interface ElementEvents extends Events {
   EventListenerList get abort();
   EventListenerList get beforeCopy();
@@ -11619,11 +11615,14 @@ interface Element extends Node /*, common.NodeSelector, common.ElementTraversal
 
   bool matchesSelector([String selectors]);
 
-  Future<ElementRect> get rect();
+  /** Only access members when [window.inMeasurementFrame] is true. */
+  ElementRect get rect();
 
-  Future<CSSStyleDeclaration> get computedStyle();
+  /** Only call when [window.inMeasurementFrame] is true. */
+  CSSStyleDeclaration get computedStyle();
 
-  Future<CSSStyleDeclaration> getComputedStyle(String pseudoElement);
+  /** Only call when [window.inMeasurementFrame] is true. */
+  CSSStyleDeclaration getComputedStyle(String pseudoElement);
 
   ElementEvents get on();
 
@@ -12486,7 +12485,7 @@ interface MutationEvent extends Event default MutationEventWrappingImplementatio
 
   Node get relatedNode();
 }
-// 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.
 
@@ -12522,6 +12521,8 @@ interface Node extends EventTarget {
   Node insertBefore(Node newChild, Node refChild);
 
   Node clone(bool deep);
+
+  bool get _inDocument();
 }
 // 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
@@ -13066,10 +13067,13 @@ interface WheelEvent extends UIEvent default WheelEventWrappingImplementation {
 
   int get y();
 }
-// 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.
 
+typedef void LayoutCallback();
+typedef LayoutCallback MeasurementCallback(); 
+
 interface WindowEvents extends Events {
   EventListenerList get abort();
   EventListenerList get beforeUnload();
@@ -13369,19 +13373,28 @@ interface Window extends EventTarget {
 
   void webkitCancelRequestAnimationFrame(int id);
 
-  // TODO(jacobr): make these return Future<Point>.
   Point webkitConvertPointFromNodeToPage([Node node, Point p]);
-
   Point webkitConvertPointFromPageToNode([Node node, Point p]);
 
   int webkitRequestAnimationFrame(RequestAnimationFrameCallback callback, [Element element]);
 
   /**
-   * Executes a [callback] after the next batch of browser layout measurements
-   * has completed or would have completed if any browser layout measurements
-   * had been scheduled.
+   * Executes [callback] after the event loop unwinds but before the page is
+   * rendered.  Inside the callback, synchronous element measurement is
+   * allowed and dom manipulation that could trigger a layout is disallowed.
+   * The [callback] may return a closure that is run in the normal
+   * context where dom manipulation is allowed but sync measurement is
+   * disallowed.
+   */
+  void requestMeasurementFrame(MeasurementCallback callback);
+
+  /**
+   * True iff within a call to [:requestMeasurementFrame:]
+   * When inside a measurement frame, any DOM manipulation that could trigger
+   * a layout is prohibited to avoid accidentally triggering large numbers of
+   * layouts.
    */
-  void requestLayoutFrame(TimeoutHandler callback);
+  bool get inMeasurementFrame();
 
   // Window open(String url, String target, WindowSpec features);