Get rid of special property_encoding flag on the LookupIterator

BUG=
R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/539083002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23695 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Use a switch over it-state to compiler handlers

BUG=
R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/541723002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23696 ce2b1a6d-e550-0410-aec6-3dcde31c8c00