We use the fast compiler only for top-level code right now.
When always_fast_compiler is set to true, we compile with
the fast compiler whereever possible.

By default this flag is set to false. 

Review URL: http://codereview.chromium.org/449012

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3381 ce2b1a6d-e550-0410-aec6-3dcde31c8c00