Move commit list out its own model.

Tools/GardeningServer/ui/ct-failure-card.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-builder-grid.html">
 <link rel="import" href="ct-commit-list.html">
 <link rel="import" href="ct-test-list.html">
 
-<polymer-element name="ct-failure-card" attributes="group commits tree">
+<polymer-element name="ct-failure-card" attributes="group commitList tree">
   <template>
     <style>
       :host {
         display: flex;
       }
 
       /* FIXME: All this paper-button styling should go in a cr-button component so that
          we can use buttons in different places and have them all look the same. */
       paper-button {
         -webkit-user-select: none;
@@ skipping 34 matching lines @@
         opacity: 0.5;
       }
 
       #examine, #snooze {
         align-self: flex-start;
       }
     </style>
     <ct-builder-grid failures="{{ group.failures }}"></ct-builder-grid>
     <div class="{{ { failure: true, snoozed: group.isSnoozed } | tokenList }}">
       <ct-test-list tests="{{ group.failures }}" tree="{{ tree }}"></ct-test-list>
-      <ct-commit-list first="{{ group.failures[0].lastPassingRevisions }}"
-          last="{{ group.failures[0].firstFailingRevisions }}"
-          commits="{{ commits }}"></ct-commit-list>
+      <ct-commit-list commitList="{{ commitList }}"></ct-commit-list>
     </div>
     <paper-button id="examine" on-tap="{{ examine }}">Examine</paper-button>
     <template if="{{ !group.isSnoozed }}">
       <paper-button id="snooze" on-tap="{{ snooze }}">Snooze</paper-button>
     </template>
     <template if="{{ group.isSnoozed }}">
       <paper-button id="snooze" on-tap="{{ unsnooze }}">Unsnooze</paper-button>
     </template>
   </template>
   <script>
     Polymer({
       group: null,
-      commits: {},
+      commitList: null,
       tree: '',
 
       examine: function() {
         this.fire('ct-examine-failures', this.group);
       },
 
       snooze: function() {
         this.group.snoozeUntil(Date.now() + 60 * 60 * 1000);
       },
 
       unsnooze: function() {
         this.group.unsnooze();
       },
     });
   </script>
 </polymer-element>