Remove extra comma to avoid fatal in IE7

jslint:
modules/jquery.wikiEditor.toolbar.config.js: line 818, col 43, Extra
comma. (it breaks older versions of IE)

Bug: 52715
Follow-Up: I8c5a52c74fa1bc83c662d748731f96bcd91374d0
Change-Id: I99c16f01176a954ad924a5c493e43fb47206fa4b