Fix eslint issues

Author: michalsnik

src/js/libs/observer.js

@@ -3,9 +3,9 @@ let callback = () => {};
 function ready(selector, fn) {
  const doc = window.document;
  const MutationObserver =
- window.MutationObserver ||
- window.WebKitMutationObserver ||
- window.MozMutationObserver;
+  window.MutationObserver ||
+  window.WebKitMutationObserver ||
+  window.MozMutationObserver;
 
  const observer = new MutationObserver(check);
  callback = fn;