Cleaned up and fixed code comment handling a bit.

* Let GCC check the arguments of LCodeGen::Coment.
* Fixed a few call sites.
* Made basic blocks a little bit more visible in the code output.
* Sorted #includes.

Review URL: https://codereview.chromium.org/14079007

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14331 ce2b1a6d-e550-0410-aec6-3dcde31c8c00