Ignore slots buffer overflow when recording entries of the allocation sites scratchpad.

BUG=
R=mstarzinger@chromium.org, ulan@chromium.org

Review URL: https://codereview.chromium.org/181063033

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19677 ce2b1a6d-e550-0410-aec6-3dcde31c8c00