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

Author: anzin

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

@@ -43,13 +43,6 @@ if (typeof window !== 'undefined' && window.document) {
         config.deps.push('es6-collections');
     }
 
-    /**
-     * 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.
      */