Revert "Update survival statistics correctly in the Scavenger."

This reverts r21991.

Reason: lots of test failures.

BUG=
TBR=hpayer@chromium.org

Review URL: https://codereview.chromium.org/352083002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21992 ce2b1a6d-e550-0410-aec6-3dcde31c8c00