thin and thick not in CSS whitelist

[gsnedders]

http://code.google.com/p/html5lib/issues/detail?id=52

Reported by scott@quadhome.com, Aug 9, 2007

CSS keywords "thin" and "thick" are not in the whitelist.

Aug 9, 2007 scott@quadhome.com

This issue was originally noticed at:

http://wiki.whatwg.org/wiki/Sanitization_rules

I assume feedparser and friends are all affected since they share the code.

(Patch dropped because it'll be as much effort to deal with changed paths and everything as to just rewrite it.)