progress bar icon changes from Kris

https://meta.discourse.org/t/expandable-topic-progress-bar/16373/10?u=codinghorror

app/assets/javascripts/discourse/controllers/topic-progress.js.es6

@@ -41,7 +41,7 @@ export default Ember.ObjectController.extend({
   },
 
   chevronClass: function() {
-    return this.get('expanded') ? 'fa-chevron-down' : 'fa-chevron-up';
+    return this.get('expanded') ? 'fa-chevron-down' : 'fa-sort';
   }.property('expanded'),
 
   streamPercentage: function() {

app/assets/javascripts/discourse/templates/topic-progress.js.handlebars

@@ -1,7 +1,7 @@
 {{#if expanded}}
   <nav id='topic-progress-expanded'>
     <button {{action jumpTop}} {{bind-attr disabled=jumpTopDisabled}} class='btn full'>
-      <i class="fa fa-arrow-circle-up"></i>
+      <i class="fa fa-caret-up"></i>
       {{i18n topic.progress.go_top}}
     </button>
     <div class='jump-form'>
@@ -9,7 +9,7 @@
     </div>
     <button {{action jumpBottom}} {{bind-attr disabled=jumpBottomDisabled}} class='btn full jump-bottom'>
       {{i18n topic.progress.go_bottom}}
-      <i class="fa fa-arrow-circle-down"></i>
+      <i class="fa fa-caret-down"></i>
     </button>
   </nav>
 {{/if}}