Correctly initialize newly created large-object pages when incremental marking with compaction is in progress.

R=erik.corry@gmail.com
BUG=v8:1737

Review URL: http://codereview.chromium.org/8070002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9475 ce2b1a6d-e550-0410-aec6-3dcde31c8c00