This change reverts r10974 which disabled those two optimizations.
They were not responsible for the problem in earley-boyer.

BUG=v8:2009
Review URL: https://chromiumcodereview.appspot.com/9699117

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11076 ce2b1a6d-e550-0410-aec6-3dcde31c8c00