af_readability: fix selector

plugins/af_readability/init.js

@@ -1,9 +1,11 @@
+/* global xhr, App, Plugins, Article, Notify */
+
 Plugins.Af_Readability = {
     orig_attr_name: 'data-readability-orig-content',
     self: this,
     embed: function(id) {
-        const content = App.find(App.isCombinedMode() ? ".cdm[data-article-id=" + id + "] .content-inner" :
-            ".post[data-article-id=" + id + "] .content");
+        const content = App.find(App.isCombinedMode() ? `.cdm[data-article-id="${id}"] .content-inner` :
+            `.post[data-article-id="${id}"] .content`);
 
         if (content.hasAttribute(self.orig_attr_name)) {
             content.innerHTML = content.getAttribute(self.orig_attr_name);