fix for sidebar toggle for safari 9.x

Author: Tubek

src/Shared/toggle-classes.js

@@ -2,5 +2,9 @@ export default function toggleClasses (toggleClass, classList, force) {
   const level = classList.indexOf(toggleClass)
   const removeClassList = classList.slice(0, level)
   removeClassList.map((className) => document.body.classList.remove(className))
-  document.body.classList.toggle(toggleClass, force)
+  if (document.body.classList.contains(toggleClass)) {
+    document.body.classList.remove(toggleClass, force);
+  } else {
+    document.body.classList.add(toggleClass, force);
+  }
 }