Extend bounds check elimination to constant keys.

R=jkummerow@chromium.org
BUG=v8:3367
LOG=N

Review URL: https://codereview.chromium.org/310333004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21672 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Fix regexp=interpreted build.

R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/318603002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21673 ce2b1a6d-e550-0410-aec6-3dcde31c8c00