Also, refactor disabling of optimization to make it easier to ensure
that both SharedFunctionInfo and Code get disabled.

R=whesse@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/7033020

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7963 ce2b1a6d-e550-0410-aec6-3dcde31c8c00