Example showing alternate async measurement solution

client/html/src/SVGElementWrappingImplementation.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 SVGElementWrappingImplementation extends ElementWrappingImplementation implements SVGElement {
   SVGElementWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
 
   factory SVGElementWrappingImplementation.tag(String tag) =>
     LevelDom.wrapSVGElement(dom.document.createElementNS(
         "http://www.w3.org/2000/svg", tag));
 
   factory SVGElementWrappingImplementation.svg(String svg) {
     Element parentTag;
     final match = _START_TAG_REGEXP.firstMatch(svg);
     if (match != null && match.group(1).toLowerCase() == 'svg') {
       parentTag = new Element.tag('div');
     } else {
       parentTag = new SVGSVGElement();
     }
 
     parentTag.innerHTML = svg;
     if (parentTag.elements.length == 1) return parentTag.elements[0];
 
     throw new IllegalArgumentException('SVG had ${parentTag.elements.length} ' +
         'top-level elements but 1 expected');
   }
 
   String get id() { return _ptr.id; }
 
-  void set id(String value) { _ptr.id = value; }
+  void set id(String value) {
+    assert(!_inMeasurementFrame || !_inDocument);
+    _ptr.id = value;
+  }
 
   SVGSVGElement get ownerSVGElement() { return LevelDom.wrapSVGSVGElement(_ptr.ownerSVGElement); }
 
   SVGElement get viewportElement() { return LevelDom.wrapSVGElement(_ptr.viewportElement); }
 
   String get xmlbase() { return _ptr.xmlbase; }
 
-  void set xmlbase(String value) { _ptr.xmlbase = value; }
+  void set xmlbase(String value) {
+    assert(!_inMeasurementFrame || !_inDocument);
+    _ptr.xmlbase = value;
+  }
 
   ElementList get elements() {
     if (_elements == null) {
       _elements = new FilteredElementList(this);
     }
     return _elements;
   }
 
   // TODO: The type of value should be Collection<Element>. See http://b/5392897
   void set elements(value) {
+    assert(!_inMeasurementFrame || !_inDocument);
     final elements = this.elements;
     elements.clear();
     elements.addAll(value);
   }
 
   String get outerHTML() {
     final container = new Element.tag("div");
     container.elements.add(this.clone(true));
     return container.innerHTML;
   }
 
   String get innerHTML() {
     final container = new Element.tag("div");
     container.elements.addAll(this.clone(true).elements);
     return container.innerHTML;
   }
 
   void set innerHTML(String svg) {
+    assert(!_inMeasurementFrame || !_inDocument);
     var container = new Element.tag("div");
     // Wrap the SVG string in <svg> so that SVGElements are created, rather than
     // HTMLElements.
     container.innerHTML = '<svg version="1.1">$svg</svg>';
     this.elements = container.elements.first.elements;
   }
 
   SVGElement clone(bool deep) => super.clone(deep);
 }