Refactor the compiling pipeline.

Goals:
 - easier to read, more suitable identifiers.
 - better distinction between compiling optimized/unoptimized code
 - compiler does not install code on the function.
 - easier to add features (e.g. caching optimized code for osr).
 - remove unnecessary code.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/110203002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18409 ce2b1a6d-e550-0410-aec6-3dcde31c8c00