Flushing of code from functions that we expect not to use again.

Flushing of code from functions that we expect not to use again.

This adds an additional step to full gc, removing code from functions
that are no longer in the compilation cache. The code is replaced with
a lazy compile version enabling us to recompile the function in case
we do actually need it again.

Review URL: http://codereview.chromium.org/2632003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4814 ce2b1a6d-e550-0410-aec6-3dcde31c8c00