[Sheriff-o-matic] Use likely_revisions instead of first_failing/last_passing

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, firstFailingRevisions, lastPassingRevisions) {
+function CTFailure(step, reason, resultsByBuilder) {
   this.step = step;
   // FIXME: Rename this to reason.
   this.testName = reason;
   this.resultNodesByBuilder = resultsByBuilder;
-  // FIXME: Move these up one layer to the groupedFailures object.
-  this.firstFailingRevisions = firstFailingRevisions;
-  this.lastPassingRevisions = lastPassingRevisions;
 }
 
 CTFailure.prototype.flakinessDashboardURL = function(tree) {
   var testType = this.step;
 
   // FIXME: Replace the flakiness dashboard's sense of groups with sheriff-o-matic's
   // sense of trees and get rid of this mapping.
   var treeToDashboardGroup = {
     blink: '@ToT%20Blink',
     chromium: '@ToT%20Chromium',
@@ skipping 40 matching lines @@
 
 // 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 [alert.master_url, alert.builder_name, alert.failing_build, alert.step_name, alert.reason].map(normalize).join('::');
 }
 </script>