Put direct code pointers into JSFunction objects. This is a first step

Put direct code pointers into JSFunction objects. This is a first step
in allowing more flexible compilation and to simplify builtins lookup.

This changes a number of places where code objects are assigned to
SharedFunctionInfo objects to also assign this code object to the
JSFunction. In addition, the code flushing is changed slightly to
accomodate this (we need to flush the code from functions pointing to
SharedFunctionInfo objects that has already been flushed).

Review URL: http://codereview.chromium.org/3120006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5233 ce2b1a6d-e550-0410-aec6-3dcde31c8c00