* Fix UC16 character classes on ASCII subjects.
* Fix sign problem in Irregexp interpreter.
* Make passes over text nodes more readable.
Review URL: http://codereview.chromium.org/21450

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1304 ce2b1a6d-e550-0410-aec6-3dcde31c8c00