Fix two glitches on bot-page

appengine/swarming/elements/res/imp/botpage/bot-page.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-page>
 
@@ skipping 127 matching lines @@
                 <template is="dom-if" if="[[_canDelete(_bot,_permissions)]]">
                   <button class="raised" on-click="_promptDelete">
                     Delete
                   </button>
                 </template>
               </td>
             </tr>
             <template is="dom-if" if="[[_bot.quarantined]]">
               <tr class="quarantined">
                 <td>Quarantined</td>
-                <td colspan="2">[[_quarantineMessage(_bot)]]</td>
+                <td colspan="2" class="message">[[_quarantineMessage(_bot)]]</td>
               </tr>
             </template>
             <tr>
               <td>Current Task</td>
               <td>
                 <a target="_blank" href$="[[_taskLink(_bot.task_id)]]">
                   [[_task(_bot)]]
                 </a>
               </td>
               <td>
@@ skipping 254 matching lines @@
         this.set("_dialogPrompt", "shut down "+this.bot_id);
         this.$.prompt.open();
       },
 
       _quarantineMessage: function(bot) {
         if (bot && bot.quarantined) {
           var msg = bot.state.quarantined;
           // Sometimes, the quarantined message is actually in "error".  This
           // happens when the bot code has thrown an exception.
           if (msg === undefined || msg === "true" || msg === true) {
-            msg = this._attribute(bot, "error");
+            msg = bot.state && bot.state.error;
           }
           return msg || "True";
         }
         return "";
       },
 
       _refresh: function() {
         this.$.data.request();
       },
 
@@ skipping 24 matching lines @@
       },
 
       _toggleState: function() {
         this.set("_show_state", !this._show_state);
       }
 
     });
   })();
   </script>
 </dom-module>