dart:html perf optimization based on runing Dromaeo benchmarks

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

-#library("dom_traverse_html");
+#library("dom_traverse");
 #import("dart:html");
 #import('../common/common.dart');
-#source("Common.dart");
-#source("RunnerSuite.dart");
+#import('runner.dart');
+
 
 void main() {
   final int num = 40;
 
   // Try to force real results.
   var ret;
 
   String html = document.body.innerHTML;
 
   new Suite(window, 'dom-traverse')
     .prep(() {
       html = BenchUtil.replaceAll(html, 'id="test(\\w).*?"', (Match match) {
         final group = match.group(1);
         return 'id="test${group}${num}"';
       });
       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.nodes.add(div);
+      document.body.appendChild(div);
     })
     .test('firstChild', () {
       final nodes = document.body.nodes;
       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.nodes.first;
+            cur = cur.$dom_firstChild;
           }
           ret = cur;
         }
       }
     })
     .test('lastChild', () {
       final nodes = document.body.nodes;
       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.nodes.last();
+            cur = cur.$dom_lastChild;
           }
           ret = cur;
         }
       }
     })
     .test('nextSibling', () {
       for (int i = 0; i < num * 2; i++) {
-        Node cur = document.body.nodes.first;
+        Node cur = document.body.$dom_firstChild;
         while (cur !== null) {
           cur = cur.nextNode;
         }
         ret = cur;
       }
     })
     .test('previousSibling', () {
       for (int i = 0; i < num * 2; i++) {
-        Node cur = document.body.nodes.last();
+        Node cur = document.body.$dom_lastChild;
         while (cur !== null) {
           cur = cur.previousNode;
         }
         ret = cur;
       }
     })
     .test('childNodes', () {
       for (int i = 0; i < num; i++) {
         final nodes = document.body.nodes;
         for (int j = 0; j < nodes.length; j++) {
           ret = nodes[j];
         }
       }
     })
     .end();
 }