Replace tagged keys for fast access by smi, and use smi in boundscheck.
BUG=
R=jkummerow@chromium.org

Review URL: https://chromiumcodereview.appspot.com/15763004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14794 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
fix thread safety issue in FunctionTemplate test

R=svenpanne@chromium.org
BUG=

Review URL: https://codereview.chromium.org/15791005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14795 ce2b1a6d-e550-0410-aec6-3dcde31c8c00