Make TaskList use Dynamic List

appengine/swarming/elements/res/imp/botlist/bot-list.html

 <!--
   Copyright 2016 The LUCI Authors. All rights reserved.
   Use of this source code is governed under the Apache License, Version 2.0
   that can be found in the LICENSE file.
 
   This in an HTML Import-able file that contains the definition
   of the following elements:
 
     <bot-list>
 
@@ skipping 337 matching lines @@
 
       properties: {
 
         client_id: {
           type: String,
         },
 
         // for dynamic table
         _columnMap: {
           type: Object,
-          value: function() {
-            return columnMap;
-          }
+          value: columnMap,
         },
         _headerMap: {
           type: Object,
-          value: function() {
-            return headerMap;
-          },
+          value: headerMap,
         },
-        // special columns contain html.  non-special (i.e. normal colunns) just
-        // contain text.
         _specialColumns: {
           type: Array,
-          value: function() {
-            return specialColumns;
-          }
+          value: specialColumns,
         },
         _specialSort: {
           type: Object,
-          value: function() {
-            return specialSort;
-          }
+          value: specialSort,
         },
 
       },
 
       _botClass: function(bot) {
         if (bot.is_dead) {
           return "dead";
         }
         if (bot.quarantined) {
           return "quarantined";
@@ skipping 33 matching lines @@
         if (data && data.task_id) {
           return "/user/task/" + data.task_id;
         }
         return undefined;
       }
 
     });
   })();
   </script>
 </dom-module>