Also remove the requirement to have an AssertNoAllocation object when getting the flat content. We actually do allow allocation, it's just GC's we don't allow.

Review URL: http://codereview.chromium.org/7710018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9001 ce2b1a6d-e550-0410-aec6-3dcde31c8c00