MC-4323: Cannot Add Slider WYSIWYG Image From Gallery or Link to Image in Gallery After Page Has Been Saved

- Fixed editor callback to use the global editor

Author: Hwashiang Yu

lib/web/mage/adminhtml/wysiwyg/tiny_mce/tinymce4Adapter.js

@@ -117,7 +117,7 @@ define([
             jQuery.when.apply(jQuery, deferreds).done(function () {
                 tinyMCE4.init(settings);
                 this.getPluginButtons().hide();
-                this.eventBus.attachEventHandler('open_browser_callback', this.openFileBrowser);
+                this.eventBus.attachEventHandler('open_browser_callback', tinyMceEditors.get(self.id).openFileBrowser);
             }.bind(this));
         },