Fix issues inserting Widgets with nested WYSIWYGs

This PR is a potential fix for issues #19742 and #13409 (Thanks to @EduardTd for pointing me in the right direction).

I've tested this briefly in my own install and it appears to resolve the issue. Submitting this PR so that the issue can be tested fully.

Author: molovo

lib/web/mage/adminhtml/wysiwyg/widget.js

@@ -456,7 +456,7 @@ define([
                     parameters: params,
                     onComplete: function (transport) {
                         try {
-                            editor = wysiwyg.activeEditor();
+                            editor = tinyMCE.get(this.widgetTargetId);
 
                             widgetTools.onAjaxSuccess(transport);
                             widgetTools.dialogWindow.modal('closeModal');
@@ -469,7 +469,7 @@ define([
                                     editor.selection.select(activeNode);
                                     editor.selection.setContent(transport.responseText);
                                 } else if (this.bMark) {
-                                    wysiwyg.activeEditor().selection.moveToBookmark(this.bMark);
+                                    editor.selection.moveToBookmark(this.bMark);
                                 }
                             }
 
@@ -513,7 +513,7 @@ define([
          * @return {null|wysiwyg.Editor|*}
          */
         getWysiwyg: function () {
-            return wysiwyg.activeEditor();
+            return tinyMCE.get(this.widgetTargetId);
         },
 
         /**