Revert "Set the state of a swept page after being done with sweeping."

This reverts commit r22514, it broke the GC stress builder.

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/405373003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22517 ce2b1a6d-e550-0410-aec6-3dcde31c8c00