MC-3812: Text/Banner - Stage Inline Editor becomes focused and editable after clicking Save button on Edit Form

- Use correct API for setting content to ensure unexpected focusing doesn’t occur

Author: davemacaulay

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

@@ -350,7 +350,7 @@ define([
          * @param {String} content
          */
         setContent: function (content) {
-            this.get(this.getId()).execCommand('mceSetContent', false, content);
+            this.get(this.getId()).setContent(content);
         },
 
         /**