Added page to Observatory to display native memory allocation information.

runtime/observatory/lib/src/elements/class_ref.dart

Index: runtime/observatory/lib/src/elements/class_ref.dart
diff --git a/runtime/observatory/lib/src/elements/class_ref.dart b/runtime/observatory/lib/src/elements/class_ref.dart
index 21bd6cce2f3798c4494584a9bfbca87c1f53c55f..bb70cb5b4455f6e45f7d6a81d38f75cad917db94 100644
--- a/runtime/observatory/lib/src/elements/class_ref.dart
+++ b/runtime/observatory/lib/src/elements/class_ref.dart
@@ -24,7 +24,6 @@ class ClassRefElement extends HtmlElement implements Renderable {
 
   factory ClassRefElement(M.IsolateRef isolate, M.ClassRef cls,
       {RenderingQueue queue}) {
-    assert(isolate != null);
     assert(cls != null);
     ClassRefElement e = document.createElement(tag.name);
     e._r = new RenderingScheduler(e, queue: queue);
@@ -50,7 +49,8 @@ class ClassRefElement extends HtmlElement implements Renderable {
 
   void render() {
     children = [
-      new AnchorElement(href: Uris.inspect(_isolate, object: _class))
+      new AnchorElement(href: (_isolate == null) ?
+          null : Uris.inspect(_isolate, object: _class))
         ..text = _class.name
     ];
   }