Replaced Element.append with Node.appendChild

samples/third_party/dromaeo/tests/dom-traverse-html.dart

 library dromaeo;
 import 'dart:async';
 import 'dart:html';
 import 'dart:json' as json;
 import '../common/common.dart';
 import 'dart:math' as Math;
 import 'dart:json' as json;
 part 'Common.dart';
 part 'RunnerSuite.dart';
 
@@ skipping 14 matching lines @@
       });
       html = BenchUtil.replaceAll(html, 'name="test.*?"', (Match match) {
         return 'name="test${num}"';
       });
       html = BenchUtil.replaceAll(html, 'class="foo.*?"', (Match match) {
         return 'class="foo test${num} bar"';
       });
 
       final div = new Element.tag('div');
       div.innerHtml = html;
-      document.body.$dom_appendChild(div);
+      document.body.append(div);
     })
     .test('firstChild', () {
       final nodes = document.body.$dom_childNodes;
       final nl = nodes.length;
 
       for (int i = 0; i < num; i++) {
         for (int j = 0; j < nl; j++) {
           Node cur = nodes[j];
           while (cur != null) {
             cur = cur.$dom_firstChild;
@@ skipping 37 matching lines @@
     .test('childNodes', () {
       for (int i = 0; i < num; i++) {
         final nodes = document.body.$dom_childNodes;
         for (int j = 0; j < nodes.length; j++) {
           ret = nodes[j];
         }
       }
     })
     .end();
 }