Some perf improvements to sheriff-o-matics updates.

Tools/GardeningServer/model/ct-failure.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>
 function CTFailure(step, reason, resultsByBuilder) {
   this.key = step + '::' + reason;
   this.step = step;
@@ skipping 50 matching lines @@
   Object.values(this.resultNodesByBuilder, function(result) {
     annotations.push(result.annotation ? result.annotation : {});
   });
   return annotations;
 };
 
 // FIXME: This should just be provided as part of the alerts feed.
 CTFailure.createKey = function(alert) {
   function normalize(str) {
     str = str == null ? '' : String(str);
-    return str.replace(/:/g, '_');
+    return str.replace(':', '_');

[esprehn, 2014/09/10 02:40:23]

This doesn't do the same thing, it used to replace all : now it only does the
first one.

   }
   return [alert.master_url, alert.builder_name, alert.failing_build, alert.step_name, alert.reason].map(normalize).join('::');
 }
 </script>