This saves one pointer per LIR instructions. The change relies on the fact
that there is a LazyBailout instruction at all the places where we need
to register a lazy deoptimization environment.

Review URL: http://codereview.chromium.org/6348016

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6441 ce2b1a6d-e550-0410-aec6-3dcde31c8c00