Merge pull request #33384 from anzin/improvement/m2-33207-remove-mutation-observer

33207: Removed lib/web/MutationObserver.js and replaced usages with native JS MutationObserver

Author: sivaschenko

app/code/Magento/Theme/view/base/requirejs-config.js

@@ -22,7 +22,6 @@ var config = {
         'mage/new-gallery': ['jquery'],
         'mage/webapi': ['jquery'],
         'jquery/ui': ['jquery'],
-        'MutationObserver': ['es6-collections'],
         'matchMedia': {
             'exports': 'mediaCheck'
         },

app/code/Magento/Ui/view/base/requirejs-config.js

@@ -36,13 +36,6 @@ var config = {
  * Adds polyfills only for browser contexts which prevents bundlers from including them.
  */
 if (typeof window !== 'undefined' && window.document) {
-    /**
-     * Polyfill MutationObserver only for the browsers that do not support it.
-     */
-    if (typeof MutationObserver === 'undefined') {
-        config.deps.push('MutationObserver');
-    }
-
     /**
      * Polyfill FormData object for old browsers that don't have full support for it.
      */