spaces (during normal allocation) and when allocating large objects.
If the promotion limit is reached, fail allocation to trigger a
garbage collection.
Review URL: http://codereview.chromium.org/8657

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@632 ce2b1a6d-e550-0410-aec6-3dcde31c8c00