Deprecation: Use Ember.Helper for later versions of Ember

app/assets/javascripts/admin/helpers/human-size.js.es6

@@ -1,3 +1,3 @@
-Em.Handlebars.helper('human-size', function(size) {
-  return new Handlebars.SafeString(I18n.toHumanSize(size));
-});
+import { htmlHelper } from 'discourse/lib/helpers';
+
+export default htmlHelper(size => I18n.toHumanSize(size));

app/assets/javascripts/admin/helpers/preserve-newlines.js.es6

@@ -1,3 +1,3 @@
-Em.Handlebars.helper('preserve-newlines', str => {
-  return new Handlebars.SafeString(Discourse.Utilities.escapeExpression(str).replace(/\n/g, "<br>"));
-});
+import { htmlHelper } from 'discourse/lib/helpers';
+
+export default htmlHelper(str => Discourse.Utilities.escapeExpression(str).replace(/\n/g, "<br>"));

app/assets/javascripts/admin/helpers/value-at-tl.js.es6

@@ -1,4 +1,4 @@
-import registerUnbound from 'discourse/helpers/register-unbound';
+import { registerUnbound } from 'discourse/lib/helpers';
 
 registerUnbound('value-at-tl', function(data, params) {
   var tl = parseInt(params.level, 10);

app/assets/javascripts/admin/templates/customize-css-html-show.hbs

@@ -32,7 +32,7 @@
         </li>
         <li class='toggle-maximize'>
           <a {{action "toggleMaximize"}}>
-            {{fa-icon-bound maximizeIcon}}
+            <i class="fa fa-{{maximizeIcon}}"></i>
           </a>
         </li>
       </ul>