Example showing alternate async measurement solution

client/html/src/DocumentWrappingImplementation.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.
 
 class DocumentEventsImplementation extends ElementEventsImplementation
       implements DocumentEvents {
 
   DocumentEventsImplementation._wrap(_ptr) : super._wrap(_ptr);
 
   EventListenerList get readyStateChange() => _get('readystatechange');
 
@@ skipping 63 matching lines @@
   /** @domName title */
   void set title(String value) { _documentPtr.title = value; }
 
   /** @domName webkitHidden */
   bool get webkitHidden() => _documentPtr.webkitHidden;
 
   /** @domName webkitVisibilityState */
   String get webkitVisibilityState() => _documentPtr.webkitVisibilityState;
 
   /** @domName caretRangeFromPoint */
-  Future<Range> caretRangeFromPoint([int x = null, int y = null]) {
-    return _createMeasurementFuture(
-        () => LevelDom.wrapRange(_documentPtr.caretRangeFromPoint(x, y)),
-        new Completer<Range>());
+  Range caretRangeFromPoint([int x = null, int y = null]) {
+    assert(_inMeasurementFrame);
+    return LevelDom.wrapRange(_documentPtr.caretRangeFromPoint(x, y));
   }
 
   /** @domName createEvent */
   Event createEvent(String eventType) {
     return LevelDom.wrapEvent(_documentPtr.createEvent(eventType));
   }
 
   /** @domName elementFromPoint */
-  Future<Element> elementFromPoint([int x = null, int y = null]) {
-    return _createMeasurementFuture(
-        () => LevelDom.wrapElement(_documentPtr.elementFromPoint(x, y)),
-        new Completer<Element>());
+  Element elementFromPoint([int x = null, int y = null]) {
+    assert(_inMeasurementFrame);
+    return LevelDom.wrapElement(_documentPtr.elementFromPoint(x, y));
   }
 
   /** @domName execCommand */
   bool execCommand([String command = null, bool userInterface = null, String value = null]) {
+    assert(!_inMeasurementFrame);
     return _documentPtr.execCommand(command, userInterface, value);
   }
 
   /** @domName getCSSCanvasContext */
   CanvasRenderingContext getCSSCanvasContext(String contextId, String name,
                                              int width, int height) {
     return LevelDom.wrapCanvasRenderingContext(_documentPtr.getCSSCanvasContext(contextId, name, width, height));
   }
 
   /** @domName queryCommandEnabled */
@@ skipping 18 matching lines @@
 
   /** @domName queryCommandValue */
   String queryCommandValue([String command = null]) {
     return _documentPtr.queryCommandValue(command);
   }
 
   /** @domName HTMLHtmlElement.manifest */
   String get manifest() => _ptr.manifest;
 
   /** @domName HTMLHtmlElement.manifest */
-  void set manifest(String value) { _ptr.manifest = value; }
+  void set manifest(String value) {
+    assert(!_inMeasurementFrame);
+    _ptr.manifest = value;
+  }
 
   DocumentEvents get on() {
     if (_on === null) {
       _on = new DocumentEventsImplementation._wrap(_documentPtr);
     }
     return _on;
   }
 }