Improve error message when attempting to evaluate against a VM-internal object (e.g., a Megamorphic…

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

 // Copyright (c) 2013, 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.
 
 library code_view_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'observatory_element.dart';
 import 'service_ref.dart';
@@ skipping 192 matching lines @@
 
   void _fillDisassemblyDOMRow(TableRowElement tr, int rowIndex) {
     final row = disassemblyTable.rows[rowIndex];
     final n = row.values.length;
     for (var i = 0; i < n; i++) {
       final cell = tr.children[i];
       final content = row.values[i];
       if (content is ServiceObject) {
         ServiceRefElement element = new Element.tag('any-service-ref');
         element.ref = content;
-        cell.append(element);
+        cell.children = [element];
       } else if (content != null) {
         cell.text = content.toString();
       }
     }
   }
 
   void _updateDisassemblyDOMTable() {
     var tableBody = $['disassemblyTableBody'];
     assert(tableBody != null);
     // Resize DOM table.
@@ skipping 150 matching lines @@
   }
 
   void mouseOut(Event e, var detail, Node target) {
     var jt = _findJumpTarget(target);
     if (jt == null) {
       return;
     }
     jt.classes.remove('highlight');
   }
 }