No longer treat the hole as a removal. This removes one branch in
Put and cleans up the API.

BUG=None
LOG=Y
R=adamk@chromium.org, mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/309663005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21616 ce2b1a6d-e550-0410-aec6-3dcde31c8c00