An attempt to retrieve security context for a function may fail if the
destination heap space is in an incomplete state. To fix this, we only
record unknown functions discovered at GC object moves, and then
register them after GC completes.

BUG=crbug/59627

Review URL: http://codereview.chromium.org/3763012

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5667 ce2b1a6d-e550-0410-aec6-3dcde31c8c00