to one by keeping a stack of active code generators and by using
indirection to handles.

Mainly a cleanup.  No visible performance impact.
Review URL: http://codereview.chromium.org/113455

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1965 ce2b1a6d-e550-0410-aec6-3dcde31c8c00