ElementsAccessor::Delete() maybehandlified.

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/230733003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20631 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/master'