Move treestatus.js to a model class.

Tools/GardeningServer/ui/ct-sheriff-o-matic.html

 <!--
 Copyright 2014 The Chromium Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
 <script src="../bower_components/sugar/release/sugar-full.development.js"></script>
 <script src="../scripts/net.js"></script>
 <script src="../scripts/results.js"></script>
-<script src="../scripts/treestatus.js"></script>
 <script src="../scripts/ui.js"></script>
 
 <link rel="import" href="../bower_components/core-animated-pages/core-animated-pages.html">
 <link rel="import" href="../bower_components/core-animated-pages/transitions/slide-from-right.html">
 <link rel="import" href="ct-results-panel.html">
 <link rel="import" href="ct-unexpected-failures.html">
 
 <polymer-element name="ct-sheriff-o-matic">
   <template>
     <style>
@@ skipping 62 matching lines @@
         this.selected = 0;
       },
 
       onExamine: function(event) {
         this.currentFailures = event.detail;
         this.selected = 1;
       },
     });
   </script>
 </polymer-element>