Example showing alternate async measurement solution

client/html/src/TextWrappingImplementation.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 TextWrappingImplementation extends CharacterDataWrappingImplementation implements Text {
   /** @domName Document.createTextNode */
   factory TextWrappingImplementation(String content) {
     return new TextWrappingImplementation._wrap(
         dom.document.createTextNode(content));
   }
 
   TextWrappingImplementation._wrap(ptr) : super._wrap(ptr);
 
   String get wholeText() => _ptr.wholeText;
 
   Text replaceWholeText([String content = null]) {
+    assert(!_inMeasurementFrame || !_inDocument);
     if (content === null) {
       return LevelDom.wrapText(_ptr.replaceWholeText());
     } else {
       return LevelDom.wrapText(_ptr.replaceWholeText(content));
     }
   }
 
   Text splitText([int offset = null]) {
+    assert(!_inMeasurementFrame || !_inDocument);
     if (offset === null) {
       return LevelDom.wrapText(_ptr.splitText());
     } else {
       return LevelDom.wrapText(_ptr.splitText(offset));
     }
   }
 }