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

Tools/GardeningServer/model/ct-commit-list-mock.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.
 -->
 
 <link rel='import' href='ct-commit-list.html'>
 
 <link rel='import' href='ct-commit-log-mock.html'>
 
 <script>
 (function () {
 
 window.CTCommitListMock = function() {
-  var group = {
-    failures: [
-      {
-        firstFailingRevisions: {
-          'blink': 158545
-        },
-        lastPassingRevisions: {
-          'blink': 158544
-        }
-      }
-    ]
-  };
-  return new CTCommitList(group, new CTCommitLogMock());
+  var revisions = ['blink:158544', 'blink:158545'];
+  return new CTCommitList(new CTCommitLogMock(), revisions);
 };
 
 })();
 </script>