Move commit list out its own model.

Tools/GardeningServer/model/ct-failure-group.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">
+
 <script>
 function CTFailureGroup(key, failures, annotation) {
   this.key = key;
   this.failures = failures;
   this.annotation = annotation || {};
   this._computeProperties();
 }
 
 CTFailureGroup.prototype.snoozeUntil = function(time) {
   return this._annotate({
     snoozeTime: time,
   });
 };
 
 CTFailureGroup.prototype.unsnooze = function() {
   return this._annotate({
     snoozeTime: undefined,
   });
 };
 
+CTFailureGroup.prototype.commitList = function(commits) {
+  return new CTCommitList(this, commits);
+};
+
 CTFailureGroup.prototype._computeProperties = function() {
   this.isSnoozed = Date.now() < this.annotation.snoozeTime;
   if (this.isSnoozed) {
     this.category = 'snoozed';
   } else {
     // FIXME: crbug.com/400397 Split into: Whole step failure, Tree closer, Test failure, Flaky tests
     this.category = 'default';
   }
 };
 
@@ skipping 23 matching lines @@
   }.bind(this));
 };
 
 CTFailureGroup.fetchAnnotations = function() {
   // FIXME: Fetch annotations from frontend.
   var stored = localStorage.CTFailureGroupAnnotations;
   var annotations = stored ? JSON.parse(stored) : {};
   return Promise.resolve(annotations);
 };
 </script>