Make first and last getters.

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

 #library("dom_traverse_html");
 #import("dart:html");
 #import('../common/common.dart');
 #import("dart:math", prefix: "Math");
 #source("Common.dart");
 #source("RunnerSuite.dart");
 
 void main() {
   final int num = 40;
 
@@ skipping 34 matching lines @@
       }
     })
     .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.nodes.last;
           }
           ret = cur;
         }
       }
     })
     .test('nextSibling', () {
       for (int i = 0; i < num * 2; i++) {
         Node cur = document.body.nodes.first;
         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.nodes.last;
         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();
 }