Automattic/_s — pull request #146 by ounziw (2013-02-01 03:31:25+00:00)
Title: $nav_id comes from outside, should be escaped.

$nav_id comes from outside, so this variable should be escaped.

Same defect found on TwentyTwelve theme. (TwentyTwelve theme is already fixed.)
https://core.trac.wordpress.org/ticket/22690