and the lookahead code for simplifying \b.  Also cache lookahead
results on the nodes, fix a memory leak and remove some character
class code we are no longer using.
Review URL: https://chromiumcodereview.appspot.com/9961009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11345 ce2b1a6d-e550-0410-aec6-3dcde31c8c00