configure ckeditor to allow unsetting font size

customize.dist/ckeditor-config.js

@@ -11,6 +11,7 @@ CKEDITOR.editorConfig = function( config ) {
     config.removePlugins= 'resize,elementspath';
     config.resize_enabled= false; //bottom-bar
     config.extraPlugins= 'autolink,colorbutton,colordialog,font,indentblock,justify,mediatag,print,blockbase64,mathjax,wordcount';
+    config.fontSize_sizes = '(Default)/unset;8/8px;9/9px;10/10px;11/11px;12/12px;14/14px;16/16px;18/18px;20/20px;22/22px;24/24px;26/26px;28/28px;36/36px;48/48px;72/72px'; // XXX translation for default?
     config.toolbarGroups= [
         // {"name":"clipboard","groups":["clipboard","undo"]},
         //{"name":"editing","groups":["find","selection"]},